*    *' 


THE 


POTATOE    PLANT, 

ITS  USES  AND  PROPERTIES  : 


TOGETHER  WITH 


THE  CAUSE  OF  THE  PRESENT  MALADY. 

THE  EXTENSION   OF  THAT  DISEASE  TO  OTHER    PLANTS,  THE 

QUESTION  OF  FAMINE  ARISING  THEREFROM,  AND  THE 

BEST  MEANS  OF  AVERTING  THAT  CALAMITY, 


BY  ALFRED  SMEE,  F.R.S. 
H 

8UHOKON  TO  THE  BANK  OF  ENGLAND;  TO  THE  ROYAL  GENERAL  DISPENSARY 

TO  THE  CENTRAL  LONDON  OPHTHALMIC  INSTITUTION  J 
AND  LECTURER  ON  SURGERY  AT  THE  ALDERSGATE  SCHOOL  OF  MEDICINE. 


ILLUSTRATED  WITH  TEN  LITHOGRAPHS. 


NEW    YORK: 
WILEY   &   PUTNAM,    161    BROADWAY. 

1847. 


J.— <t-A-/-CX^ 

0 


R.  CRAIOHKAD,  HttNTKR,  112  FULTON  BTRKBT,  NEW  YORK 


I<J  c*  I  ( 


TO 


HIS     ROYAL    HIGHNESS 


THE  PRINCE  ALBERT,  K.G.,   F.R.S 


SIR, 

I  FEEL  MOST  DEEPLY  THE  HONOR  WHICH  YOUR  ROYAL 

HIGHNESS    HAS    CONFERRED    UPON    ME    IN  CONDESCENDING 
TO    ALLOW    ANOTHER    TREATISE    TO    BE    DEDICATED    TO  YOUR 

ROYAL  HIGHNESS. 

IN  SUBMITTING  THE  RESULT  OF  MY  LABORS  TO  YOUR 

ROYAL    HIGHNESS,    I    REJOICE    IN  THE  BELIEF  THAT 

THE  DISCOVERY  OF  THE  CAUSE  OF  THE  PRESENT  SCARCITY 

WILL  LEAD  THE  NATION  TO  EMPLOY  THE  BEST  MEANS  OF 
AVERTING  THE  PROGRESS  OF  THE  CALAMITY. 

I  HAVE  THE  HONOR  TO  BE, 

SIR, 
YOUR  ROYAL  HIGHNESS'S 

MOST  DUTIFUL  SERVANT, 

ALFRED  SMEE. 


M671301 


PREFACE. 


WHEN  a  great  Calamity,  arising  from  some  un- 
known cause,  comes  over  the  human  race,  every 
individual  feels  the  deepest  interest  in  ascertaining 
the  agent  which  has  given  rise  to  the  mischief. 
Hence  I  was  led  to  inquire  into  the  present  potatoe 
malady,  but  had  no  idea,  in  the  first  instance,  that  a 
volume  would  have  been  written  to  record  my 
observations. 

The  result  of  my  inquiries  might  have  been  con- 
veyed in  a  few  words,  had  there  been  no  other 
observations  published  upon  the  subject.  I  have 
now,  however,  been  compelled  to  consider  all  the 
assumed  causes  of  this  malady,  which  have  been 
already  promulgated  by  scientific  men. 

It  is  to  be  regretted  that  some  of  our  most  respect- 
ed philosophers  should  have  committed  themselves 
early  in  this  matter.  For  now,  I  fear,  in  some  cases, 
they  will  not  like  to  reconsider  their  opinion ;  and 
should  this  be  the  case,  they  must  necessarily  act 
as  opponents  to  all  other  rationalia  of  this  lamented 
malady. 


VI  PREFACE. 

I  have  to  apologize  to  Entomologists  for  having 
violated  an  established  rule,  by  changing  the  name 
of  an  insect ;  I  found,  however,  that  such  confusion 
would  attend  my  adoption  of  their  name,  "  Rapae," 
or  turnip,  for  the  destroying  Aphis,  that  I  at  once 
determined,  for  the  sake  of  perspicuity,  to  call  it  in 
my  work  the  "  Vastator." 

This  work  has  required  some  labor  in  its  pre- 
paration ;  at  times  I  have  frequently  had  to  tra- 
verse many  miles,  in  order  to  determine  a  single  fact. 
For  the  purpose  of  ascertaining  the  existence  of  the 
disease  in  any  plant,  it  was  not  sufficient  merely  to 
examine  it  in  one  locality  ;  it  might  not  have  been 
attacked  at  that  spot ;  the  insect  might  have  left  the 
plant,  or  the  plant  might  not  grow  in  the  place  which 
I  visited. 

This  work  also  required  a  knowledge  of  Botany, 
Entomology,  Chemistry,  and  Agriculture.  I  cannot 
be  expected  to  be  conversant  with  all  these 
matters,  for  each,  alone,  would  take  a  long 
lifetime  to  acquire.  I  am  therefore  fully  aware 
of  the  great  imperfection  of  the  work  in  these 
particulars  ;  but  I  trust  that  the  development  of  the 
Cause  of  the  disease  in  the  potatoe,  and  the  disco- 
very that  it  attacks  other  plants,  will  prove  useful  to 
mankind. 

As  soon  as  I  perceived  that  it  would  be  necessary 
to  write  a  small  Treatise  on  the  subject,  I  pressed 
numerous  friends  into  my  service,  and  I  obtained 
valuable  assistance  in  numerous  quarters.  To  all 


PREFACE.  VU 

these  friends  my  best  thanks  are  due.  1  am,  how- 
ever, more  especially  bound  to  return  my  grateful 
acknowledgments  to  Mr.  INGALL,  Deputy  Principal 
of  one  of  the  Stock  offices  of  the  Bank  of  Eng- 
land. This  gentleman,  although  his  labors  at  the 
Bank  are  sufficiently  arduous,  has  yet  found  time  to 
make  one  of  the  finest  private  collections  of  in- 
sects in  this  country,  and  is,  besides,  an  ardent  cul- 
tivator of  the  sciences  of  Natural  History  and 
Botany. 

The  service  which  he  has  rendered  to  me  in  this 
work  is  of  such  value,  that  the  Volume  could  hardly 
have  been  produced,  in  its  present  form,  without  his 
aid ;  for  he  made  all  the  Drawings,  which  I  have 
been  enabled  to  lay  before  my  readers,  and  arranged 
the  plates  for  the  artist. 

I  have  also  to  thank  my  pupils,  Mr.  LATHAM  and 
Mr.  GREATREX,  for  procuring  me  various  informa- 
tion. 

To  Mr.  THOMPSON,  the  indefatigable  and  learned 
Librarian  of  the  London  Institution,  I  have  to  tender 
my  grateful  acknowledgments  for  the  aid  which  he 
afforded  me  in  referring  to  works  and  in  copying 
plates. 

To  -my  old  and  kind  friend  Mr.  JOHN  BEADNELL, 
Jun.,  I  have,  as  on  former  occasions,  to  render  my 
best  thanks,  for  revising  the  entire  proof  sheets  of 
this  work.  And  my  excellent  friend  Dr.  FERGUS  I 
have  also  to  thank  for  the  compilation  of  the  Analyti- 
cal Index. 


DIRECTIONS  TO  THE  BINDER. 


PLATE 

I.  ,r       ;.-,       .T,        f^          .            To  face  the  Title. 

II.  .            .           V         £           .            ,            •         Page     1 

III.  .        -^  '    y^      ^.~-    H'-'.  ?        .        'T"        55 

TV.  -...-  "„,;"•  -v1-.^    $p  -    v       •       V ?      -     57 

V.  ...            .             .             .            ...        63 

VI.      ...    ^ 59 

VII.  "TV         .            .            .            V            .             .             26 

vni.  .         ;        V-T  i   ;         i ;       .          .         .     64 

IX.  . i.  (        65 

X.  103 


C  0  N  T  E  N  T  S  . 


CHAPTER  I. 

ON    THE    POTATOE    PLANT. 

Parts  of  Potatoe  plant  (1);  set  (2);  stalk  (3). — Under-ground 
stem  and  tuber  (5-7) ;  roots  (8) ;  haulm  (9)  ;  flowers  and  fruit 
(10). — Essential  parts  of  plants  (11,  12). — Ultimate  parts  of  pota- 
toes (13-16). — Origin  of  starch  (17). — Origin  of  nitrogen  (18).— 
Motion  of  sap  (19,  20). — Experiments  on  Endosmosis  (21). — 
Quantity  of  water  imbibed  by  roots  (22).— Resume  (23). — 
PAGE  1. 


CHAPTER  II. 
INDIVIDUALITY    OF    THE    POTATOE    PLANT. 

Individuality  of  the  potatoe  plant  (24).— Plurality  of  individuals 
(25). — Individuals  are  seedlings  (26 — 29). — Duration  of  indivi- 
duals (30). — Potatoe  botanically  considered  (31). — Gerard's  de- 
scription (32 — 34).— Introduction  of  potatoe  (35,  36). — Wild 
potatoes  (37). — Humboldt's  account  (38,  39). — Meyer's  account 
(41).— Don  Jose  Pavon  (42).— Caldcleugh  (43— 46),— Chelsea 
wild  root  (47— 49).— Uhde  (50).— Origin  of  our  varieties  (51).— 
Number  of  (52). — Propagation  of  (53). — Selection  of  (54).— Ana- 
logies of  varieties  (55,  56). — Sweet  potatoe  (57 — 59). — Origin  of 
name  (60). — Resume  of  the  chapter  (61).— PAGE  6. 
B 


X  CONTENTS. 

CHAPTER  III. 

CHEMISTRY    AND   USES    OF    THE    POTATOE. 

Ingredients  of  potatoe  (62).— Analyses  of'potatoe  (63,  64).— Sola- 
nine  (65). — Starch  (66). — Albumen  (67). — Ultimate  analyses  of 
potatoe  (63). — Gerard's  description  of  (69).— Evelyn's  (70). — Use 
of  the  potatoe  (71,  72).— Relative  value  of  potatoe  (73).— Quantity 
required  for  food  (74). — Phosphorus  in  potatoe  (76,  77).— Aphro- 
disiac properties  (78)  — Iron  in  potatoe  (79). — Modes  of  cooking 
(81). — Use  of  potatoe  for  bread  (82). — Potatoe  in  wheaten  bread 
(83).— Potatoe  a  medicine  (84).— Extraction  of  starch  (85—87). 
— Uses  of  starch  (88 — 90). — Conversion  of  starch  into  dextrine 
(91) ;  into  sugar  (92). — Potatoes  used  for  the  manufacture  of 
spirit  (93,  94). — Frosted  potatoes  used  for  spirit  (95) ;  for  wine 
(96). — Potatoes  for  feeding  cattle  (97) ;  sheep  and  swine  (98). — 
Potatoe  apples  for  salad  (99). — Preserved  potatoes  (100). — Resume 
(101).— PAGE  17, 


CHAPTER  IV. 

ON    THE    GANGRENE    OF    THE    POTATOE,    OR    PRESENT    DISEASE 
IN    THE    PLANT. 

Disease  of  potatoe  (102). — Mortification  (103). — Commencement  of 
and  propagation  in  leaves,  stalks  (104 — 107) ;  in  under-ground 
stem  (108);  in  collar  (109).— Modes  of  proceeding  (110 — 113); 
in  tubers  (114) ;  in  seeds  (120). — Odor  in  (121). — Dryness  of  leaf 
in  (122). — Diseased  plants  (123). — Plants  not  injured  (124); 
afterwards  die  (125). — Primary  effect  (126). — Entire  plant  dis- 
eased (128).— Top  of  haulm  left  (129— 132).— Continuity  of  dis- 
ease in  future  plants  (132). — Period  of  growth  when  affected  by 
disease  (134—136). — Diseased  potatoes  bad  (136). — Structure 
impaired  (137). — Decomposed  (138 — 141). — Irregular  cavity  (142, 
143). — Shrivelling  of  (143.) — General  character  of  alteration 
(144).— PAGE  28. 


CONTENTS.  XI 

CHAPTER  V. 

;W,V,      CHEMISTRY    OF    DISEASE. 

Diseased  tuber  different  in  quality  (145).— Mode  of  analysis  (147). — 
Value  of  analyses  (148). — Analyses  (149)  —Deficiency  of  fibre 
(150). — Starch  in  excess  (151). — Albumen  destroyed  (152).— 
Solly's  analysis  (153). — Diseased  potatoes  partially  destroyed 
(154). — Sugar  in  diseased  potatoes  (157). — Butyric  acid  (158); 
liable  to  fermentation  (159,  160). — Difference  between  the  sound 
and  diseased  potatoes  (161). — PAGE  37. 

CHAPTER  VI. 
RELATION    OF   THE    DISEASE    TO  INTERNAL    CAUSES. 

Gangrene  from  old  age  (164). — Kinds  not  equally  affected  (165). — 
Progress  of  disease  in  Chelsea  wild  plant  (166)  ;  in  Uhde's  plant 
(167) ;  in  various  varieties  (168)  ;  in  plants  requiring  much  leaf 
(170). — Horticultural  Society's  plant  (172). — Greatrex's  account 
(175). — Storr's  account  (176). — Latham's  account  (177). — Early 
varieties  less  liable  to  disease  (179). — PAGE  42. 

CHAPTER  VII. 

RELATION   OF   THE   DISEASE   TO   EXTERNAL   CAUSES,  TEMPERA- 
TURE, LIGHT,  ELECTRICITY,  ETC. 

Gangrene  not  the  result  of  any  internal  cause  (180). — Effect  of  tem- 
perature upon  plants  generally  (181). — Potatoe  thrives  in  various 
climates  (182). — Cold  (184).— Influence  of  temperature  (185)  ; 
upon  the  decay  of  tubers  (187). — Effect  of  light  upon  plants 
(190).— Effects  of  light  upon  tubers  (193).— Influence  of  electri- 
city (194). — Influence  of  atmospheric  moisture  on  plants  (195). — 
Excessive  moisture  a  cause  of  disease  (196) ;  its  influence  on  the 
disease  (197);  effect  on  the  tubers  (199);  other  atmospheric 
agents  (200).— Effect  of  winds  (201).— PAGE  47. 


Xl  CONTENTS. 

CHAPTER  VIII. 

•RELATION    OF   DISEASE    TO    SOILS    AND    MANURES. 

Soil  which  suits  the  potatoe  (205). — Diseased  in  all  soils  (206). — 
Statement  of  Mr.  Latham  (207)  ;  of  Mr.  Greatrex  (209).— Influ- 
ence of  wet  soils  on  the  disease  (211). — Guano  and  Animal  Salts 
(214). — Influence  of  manures  on  the  disease  (216). — PAGE  52. 

>  CHAPTER  IX. 

RELATION    OF    DISEASE    TO    FTINGI. 

Berkeley's  opinion  (217). — Fungi  common  to  decaying  matter 
(219). — Fungi  on  decaying  tubers  (221).— Botrytis  infestans  (223). 
— Fungus  in  the  inside  of  tubers  (226). — Different  fungi  growing 
in  rotten  tubers  (227— 230.)— Black  fungus  on  stem  (231).— 
Other  species  of  fungi  (232,  233)  — Singular  appearance  of  motion 
in  fungi  (234). — Fungi  influence  the  disease  (237).— Fungi  fulfil 
important  functions  in  nature  (238— 240).— Gangrena  sicca  and 
humida  (241). — Tubers  infected  with  fungi  perhaps  injurious  as 
food  (242).— PAGE  55. 

CHAPTER  X. 

RELATION    OF    GANGRENE    TO    ANIMAL    PARASITES. 

Numerous  species  of  insects  on  potatoe  plant  (244)  — Acarus  (245). 
Coccinella,  ichneumons,  flies  (247). — Aphis  (248). — PAGE  61. 

CHAPTER  XI. 
APHIS    VASTATOR. 

Insect  on  the  potatoe  plant  (249—250) ;  its  color  (252) ;  dimen- 
sions (256— 259).— Suctorial  apparatus  (260);  head  and  eyes 
(261)  ;  abdomen  and  tubercles  (262) ;  pupa  (263) ;  imago,  or  per- 


CONTENTS.  XH1 

feet  insect  (264) ;  named  "  vastator,"  and  why  ('265). — Curtis' 
description  (266).— Astonishing  fecundity  (267 — 269).— Continu- 
ance of  the. species  (270 — 273). — Mode  of  attack  on  the  plant 
(274,  275).— Restlessness  of  the  insect  (276— 278).— Flight  of 
the  insects  (281,  282).— Progress  of  the  mischief  (283—285).— 
Action  on  different  varieties  (286,287). — Effect  of  moisture  after 
attack  (288,  289).— Attack  at  different  ages  of  the  plant  (290, 
291). — Relation  of  the  disease  to  this  insect  (292 — 294).— 
PAGE  63. 

CHAPTER  XII. 

TURNIP    DISEASE. 

White  turnips,  method  of  attack  thereon  (296,  297).— Effects  of  the 
attack  (298— 301).— Spiral  vessels  (302,  303).— Effluvia  from  rot 
(304).— Effects  of  time  (305,  306).— Fungi  (307).— Aphis  bras- 
sicae,  description  of,  (309,  310);  its  habits  (311,  312). — Swede 
turnip  (316). — Conclusion  (318). — PAGE  73. 


CHAPTER  XIII. 

BEET,    SPINACH,    AND    CARROT    DISEASE. 

Beet  attacked  by  the  Aphis  (319). — Mode  in  which  the  disease  pro- 
gresses (320 — 322). — Number  of  insects  on  a  plant  (323). — An- 
other species  of  Aphis  (324). — Spinach  attacked  (325). — Effects 
of  attack  (326). — Action  of  disease  (327). — Effect  of  rain  on  dis- 
eased plant  (328).— Carrot  subject  to  the  disease  (329).— Opera- 
tion of  disease  upon  it  (330,331). — Disease  identical  in  all  plants 
attacked  (332).— PAGE  79. 


CHAPTER  XIV. 

THE    APHIS    VASTATOR    ON    OTHER   PLANTS. 

Solanum  dulcamara  and  nigrum  attacked  by  the  vastator  (334). — 
Its  effect  upon  them  (335). — Greenhouse  and  other  species  of 


XIV  CONTENTS. 

solanum  (336). — Atropa  belladonna  (337).— Hyoscyamus  (338). 
—Tobacco  not  attacked  (339). — Stramonium  attacked  (340). — 
Comparative  effects  on  wild  and  cultivated  plants  (341). — Mode 
of  operation  (342). — Numerous  cruciferous  plants  attacked  (343, 
344).— Horse-radish  (345).— Tomato  (346).— Vastator  on  Indian 
corn  (347). — On  wheat  (348 — 351). — Not  on  the  oat  (352). — 
Wild  barley  grass  (354). — Seedling  pasture  grass  (355). — Jerusa- 
lem artichoke  (357).— Nettle  (358)  —Mallow  (359).— Hearts- 
ease (360). — Coreopsis  tinctoria  and  Balsam  (361). — Parsnip 
(362).— Chickweed  (363)  —Young  elders  (364). — Geranium  molle 
(365).— Plantain  (366).— Groundsel  (367).— Shepherd's  purse 
(368).— Spurge  (369).— Marigold  and  Thistles  (370).— Peach  and 
Nectarine  (371).— Celery  (372).— Probably  other  plants  also 
(373).— Remark  (374).— PAGE  83. 


CHAPTER  XV. 

INJURIES    SIMILAR   TO    THOSE    CAUSED   BY    THE    VASTATOR, 
PRODUCED    BY    OTHER    APHIDES. 

Aphides,  numerous  species  of  (375).— Aphis  of  the  hop  (376). — 
Aphis  of  the  cabbage  and  turnip  (377). — Aphis  of  the  pea  (378). 
—Instance  of  mischief  by  [Kirby]  (379). — Bean  aphis  (380). — 
Apple-tree  aphis  (381).— Sugar-cane  (382). — Aphis  of  larch 
(383).— Rose-tree  aphis  (384). — Aphis  on  couch-grass  (385).— 
Aphides  generally  (386).— PAGE  91 


.  CHAPTER  XVI. 

ON    THE    EXCESSIVE     APPEARANCE     OF     PARTICULAR    INSECTS. 

Natural  balance  in  the  relative  numbers  of  living  creatures  (3S7). — 
This  balance  occasionally  disturbed  (388). — Excessive  appear- 
ance of  Aphis  vastator  (389).— Instance  at  Brighton  (390).— 
Insect  plagues  recorded  in  the  Old  Testament  (391). — Kirby  and 
Spence  (392). — Ravages  of  the  May-beetle  (393,  394). — Ravages 
of  several  species  of  insects  (395,  396). — Bostrichus  typographus 


CONTENTS.  XV 


(397).— Locust  plagues  (398,  399).— Wasps  (401).— Honeydew 
(402). — Controlling  agents  (404). — The  exaggerated  increase  of 
particular  insects  not  continuous  (405). — PAGE  95. 


CHAPTER  XVII. 

RELATION     OF     THE    VASTATOR     TO     OTHER    APHIDES    AND    TO 
FUNGI. 

Analogy  between  the  different  aphides  (406 — 409). — Probable  effect, 
of  the  predominance  of  one  species  (410). — Destructive  power  of 
aphis  (411).— Relation  of  fungi  to  aphides  (412).— PAGE  101. 


CHAPTER  XVIII. 

NATURAL     REMEDIES     FOR     THE     PRESENT     DISEASE     AMONG 
PLANTS. 

Animals  destructive  to  aphides  (413). — Coccinelia  (414,  415) ; — 
Profusion  of  (416).— The  Gauze-wing  (418). — Larvae  of  Sylphidae 
(419).— Parasitic  Hymenoptera  (420,  421). — Other  Hymenoptera 
(422). — Earwing  and  species  of  Acarus  (424). — Spiders  (425). — 
The  soft-billed  birds  (426,  427). — Ducklings  (428).— PAGE  103. 


CHAPTER  XIX. 

RELATION    OF    THE    GANGRENE     TO     OTHER    DISEASES    OF    THE 
POTATOE. 

The  curl  (430,  431). — Hollins'  description;  varieties  of  curl  (432 — 
434). — Putsche  and  Vertuch's  description  (435). — Curl  probably 
identical  with  present  disease  (436). — Curl  from  attack  of  vastator 
(437).— The  rust  (438).— PAGE  108. 


XVI  CONTENTS. 

CHAPTER  XX. 
THEORY    OF    THE    DISEASE. 

Resume  of  the  various  supposed  causes  of  disease  (439,  440). — 
Vastator  (441).— The  disease  (443). — Condition  of  plant  causing 
death  (444,  445). — Effect  of  disease  on  wild  plants  (440).— On 
cultivated  plants  (447). — Propagation  from  diseased  sets  (448, 
449). — As  to  cessation  of  disease  (450). — Relation  of  health  of 
plant  to  the  insect  (451,  452).— PAGE  111. 

CHAPTER  XXI. 
FUTURE    PROSPECTS    OF    THE    DISEASE. 

Mischief  done  to  esculent  vegetables,  &c.,  by  vastator  (454). — Dura- 
tion of  insect  pests  :  historical  analogies  (455). — Probabilities  as 
to  increase  of  the  plague  (456,  457). — Aphis  brassicae  (458). — 
Insect  destroyers  of  vastator  (459). — Probable  result  of  disappear- 
ance of  vastator  (460) ;  of  continuance  (461) ;  of  increase  (462). — 
Concluding  remarks  (463). — PAGE  115. 

CHAPTER  XXII. 
ARTIFICIAL    REMEDIES    FOR    THE    POTATOE    DISEASE. 

Division  of  subject  (464). — Destruction  of  Aphis  considered  :  by 
human  means  (465) ;  by  tobacco  (466).— Effects  of  water,  thunder- 
storm, on  Aphis  rosae  (467)  ;  on  vastator  (468). — Burning  infected 
leaves  (460)- — Effect  of  leaf-burning  in  beet  (470). — Quicklime 
(471).— Ducks  and  soft-billed  birds  (472).— Coccinellse  and  ich- 
neumons (473).— Wheat  (474). — Early  ripening  (475).— Early 
potatoes  (476). — Autumn  planting  (477). — Recapitulation  (478). — 
Contagion  (479). — Burning  infected  haulms  (480). — Isolation  of 
crops  (481). — Means  to  be  adopted  over  large  districts  (482). — 
Same  means  for  all  crops  (483). — Prppagation  from  healthy  sets 
(484).— Generation  of  fibre  (485). — Means  of  inducing  this  (486). 


CONTENTS.  XV11 

—Sets  (487).— Varieties  resembling  the  wild  potatoe  (488).— 
Planting  in  sand  or  peat  (489). — Dryness,  warmth,  and  light 
(490). — Propagation  of  the  young  stalks  (491,  492).— Requisites 
for  healthy  propagation  (493,  494). — Diminished  starch  (495). — 
Starch  cells  (49ti). — Remedies  which  have  been  proposed  (497). — 
Drying  (498).— Cold  and  dryness  (499).— Review  (500). — 
PAGE  118. 

CHAPTER  XXIII. 

ON    FAMINES. 

Equalization  of  food  (501). — Deficient  crops  (502).— Enumeration 
of  famines  (503). — Inefficient  legislation  as  to  public  health 
(504). — Proposed  remedy  (505). — Duties  of  a  council  of  health 
(506 — 508). — Precautionary  measures  (509). — Absolute  duties  of 
the  executive  (511 — 512). — Table  of  esculents  attacked  by  vastator 
and  other  aphides  (513).— Other  nutritive  matter  (514 — 517).— 
Excise  laws  (518) ;  the  year  1845  (519)  ;  1846  (520).— Conclud- 
ing remraks  (521— 522).— PAGE  128. 

CHAPTER  XXIV. 
ON    THE    APPLICATION    OF    DISEASED    POTATOES. 

Diseased  potatoes  as  food  (523). — Thompson's  lectures :  damaged 
wheat  (524) ;  effects  of  (525) ;  difficulty  of  experimenting  on 
animals  (526).— Effects  of  mouldy  food  (527).— Probable  effects 
of  diseased  potatoes  on  man  (528 — 529) ;  on  animals  (530 — 531) ; 
for  fattening  bullocks,  feeding  milch  cows  (532). — Used  by  bakers 
(533).— Vitiated  food  generally  (534— 535).— Starch  (536—539). 
—PAGE  134. 

CHAPTER  XXV 
THE    BENEFITS    AND    THE    DANGERS    OF    THE    POTATOE. 

Value  of  the  potatoe  (540).— Culture  (541).— Nutritive  power  (542, 
543). — Exclusive  potatoe  culture,  moral  effects  (544) ;  physical 
effects,  the  Irish  (546,  547),— Dangers  of  (548).— PAGE  138. 


XV111  CONTENTS. 

RESUME 140 

APPENDIX  /r*>,    i!r,..  .. .  f.^..,  .  mj>v'  ^^       •         »         •  145 

INDEX  151 


EXPLANATION  OF  THE  PLATES. 


PLATE  I. 

FAC-SIMILE  of  the  wood-engraving  printed  in  Gerard's  "  Herb- 
al," which  is  the  first  figure  of  this  plant,  and  shows  the  general 
characteristic  of  the  plant  at  its  introduction. 

PLATE  II. 

FIG.  1.  Diagram  of  the  potatoe  plant,  to  show  its  mode  of 
growth,  particularly  with  respect  to  the  formation  of  the  tubers. 

a  Original  set.  b  Stem.  c  Collar.  d  Above  ground  stem. 

e  Fruit.  /Leaf.  A  Axil  of  the  leaf.  j  Flower. 

k  Under-ground,  or  tuber-bearing  stem.  These  stems  are  given  oft'  chiefly  in 
two  places,  the  upper  one  of  which  arises  after  the  plant  is  earthed  up,  and  shows 
the  utility  of  the  process. 

I  Tuber. 

TO  Tuber  growing  from  a  former.  This  second  tuber  takes  the  starch  from  the 
first  (s),  and  renders  it  useless;  and  this  continues  to  grow,  taking  the  starch  from 
the  further  part  of  its  own  tuber,  so  that  one  end  is  good,  the  other  worthless. 

n  Above-ground  stem  growing  from  a  tuber-bearing  stem. 

o  Tuber  with  roots,  which  is  an  unusual  occurrence. 

r  True  roots  of  the  plant. 

2'.  Botrytis  infestans,  after  Berkeley,  showing  the  manner  in 
which  it  ramifies  amongst  the  cellular  tissue  of  the  leaf.  This 
figure  is  highly  magnified. 

PLATE  III. 

FUNGI  (Smee). 

All  these  are  highly  magnified. 

FIG.  1 .  Fungi  found  on  rotten  potatoes,  either  on  cut  sections 
or  in  cavities  arising  from  the  shrivelling  of  potatoes,  or  thrusting 
up  the  cuticle,  and  thus  appearing  in  great  masses. 


XX  EXPLANATION  OF  THE  PLATES. 

a  Young  top.  I  In  a  more  mature  state. 

c  Showing  its  appearance  when  it  is  quite  ripe,  and  throwing  the  spirals. 

2.  Black  fungus  (probably  Prolomyces),  in  a  stalk,  slightly 
magnified. 

3.  One  patch  alone,  more  strongly  magnified.     This  is  found 
in  the  tuber,  as  well  as  the  haulms. 

4.  A  fungus  probably  allied  to  fig.  1. 

5.  A  fungus  with  small  heads,  which  resembles  the  Medusa's 
head  under  a  powerful  micoscrope. 

6.  A  fungus  (probably  Botrytis),  from  the  edge  of  the  leaf. 
The  lithographer  has  rather  sacrificed  the  distinctness  of  the 
mode  of  fructification. 

7.  A  fungoid  growth  upon  the  Aphis  vastator,  much  resembling 
that  found  in  the  scald-head  of  man. 

PLATE  IV. 

FUNGI  (Smee), 

All  these  are  highly  magnified. 

FIG.  1.  The  leg  of  the  Aphis  vastator,  showing  a  parasitic 
fungus. 

2  and  3.  Delicate  fungus  often  growing  upon  diseased  tubers. 

4.  A  singular  fungus,  resembling  a  rush.     I  do  not  know 
whether  it  is  in  a  persistent  state,  and  I  have  only  observed  one 
example  of  it. 

5.  A  very  beautiful  and  abundant  fungus,  often  to  be  found  on 
the  exterior  of  decaying  tubers,  or  on  a  cut  section.     It  is  appa- 
rently of  a  brown  color,  like  oxide  of  iron,  but  under  the  micro- 
scope shows  this  beautiful  and  distinct  form.     One  of  the  draw- 
ings is  more  highly  magnified  than  the  rest. 

6.  A   fungus    (probably   Botrytis'),  from  under-ground  stem. 
This  appeared  somewhat  similar  to  the  Botrytis  of  Berkeley,  ex- 
cept that  the  top  was  more  globular. 

7  and  8.  Fungi  from  under-ground  stem. 
9.  Fungi  from  diseased  tubers. 


EXPLANATION  OF  THE  PLATES.  Xx 

PLATE  V. 

VARIOUS   SUBJECTS. 
All  the  figures  but  fig.  4  are  magnified. 

1.  Empty  cell,  after  Martius. 

a  Light  yellow  grains  of  Protomyces. 
b  Fungous  fibre  commencing. 

2.  Beautiful  fungus  found  on  under-ground  stem.     (Smee.} 

3.  Botrytis,  after  Berkeley. 

4.  Leaf,  showing  the  manner  in  which  it  evinces  the  gangrene 
and  blotches. 

5.  Starch  granules,  after  Pereira,  showing  their  external  ap- 
pearance. 

a  Normal  starch  particles. 

b  Irregular. 

c,  d  Particles,  each  having  two  hila. 

e,  g  Particles  broken  by  pressure  and  water,  the  internal  matter  remains  solid. 

6.  Thrips  munilissima,  after  a  drawing  from  the  "  Gardener's 
Chronicle." 

7.  Eupteryx  solani,  after  a  drawing  from  the   "  Gardener's 
Chronicle." 

8.  Acarus  farina,  which  is  found  abundantly  on  diseased  po- 
tatoes. 

9.  Red  Acarus,  which  preys  upon  Aphides. 

10.  A  species  of  Aphis  which  was  noticed  upon  a  potatoe  plant. 

PLATE  VI. 

FUNGI   AND   DISEASED    STRUCTURE,  AFTER    MARTIUS. 
All  the  figures  are  highly  magnified. 

FIG.  1.  A  part  of  the  epidermis  of  a  white  potatoe  separated 
by  a  horizontal  cut.  (Plate  in.,  fig.  17.) 

2.  Vertical  section  through  the  epidermis  of  a  white  potatoe 
to  the  cells. 


XX11  EXPLANATION    OF    THE    PLATES. 

a  Cells  of  the  epidermis.  b  Cells  under  them  pressed  together. 

c  Common  cellular  tissue.    At  *  is  seen  a  small  forked  fibre,  and  four  small 
bodies,  the  presumed  commencement  of  the  fungus.     (Plate  in.,  fig.  18.) 

3.  Horizontal  section  of  the  cellular  tissue,  in  which  the  cells 
are  partly  torn.     (Plate  in.,  fig.  19.)       ^ 

4.  Section  of  a  fungoid  excrescence  from  top  to  bottom. 

o  Healthy.  ft  Diseased  cell.  c  Epidermis. 

d  Exhausted  cellular  tissue,  which  serves  as  a  matrix  for  the  fungoid  growth. 
e  The  fungus  surrounded  and  entangled  by  cellular  tissue  raised  at  /.    (Plate 
in.,  fig.  22.) 

5.  A  very  young  fungus,  growth  intersected  by  grains  of  Pro- 
tomyces  strongly  magnified.     (Plate  HI.,  fig.  23.) 

6.  Vertical  section  of  an  excrescence  of  which  the  fungus  is 
fully  developed. 

b  Decayed  cellular  tissue  under  the  epidermis. 

c,  d  Empty  cellular  tissue,  serving  as  the  foundation  for  the  fungus. 

e  Part  of  the  cellular  tissue. 

/  A  dense  mass  of  upright  flakes  of  Fusisporium  solani.  (Plate  m.,  fig.  25.) 

7.  Separate  portions  of  fungus  highly  magnified.     (Plate  m., 
fig.  26.) 

8  and  9.  Fusisporium  solani  at  a  more  advanced  stage  with 
seed  grains  fully  developed.     (Plate  HI.,  figs.  27,  28.) 

10.  A  ripe  seed  grain  more  strongly  magnified.     (Plate  m., 
fig.  29.) 

11.  A  single  fungous  fibre  with  its  seed  grain,  showing  its 
changes  after  being  moistened  with  vitriolic  acid.      (Plate  in., 
fig.  30.) 

PLATE  VII. 

FIG.  1.  Section  of  a  diseased  carrot,  showing  the  manner  in 
which  it  rots  in  consequence  of  the  disease.     (Natural  size.) 

2.  Section  of  diseased  turnip  in  the  first  stage  of  the  disease, 
showing  that  the  malady  evinces  itself  principally  between  the 
spiral  vessels  and  bark.     (Natural  size.) 

3.  Section  of  a  potatoe  in  the  first  stage  of  gangrene,  showing 


EXPLANATION    OF    THE    PLATES.  XX111 

that  the  disease  in  the  first  instance  is  most  prone  to  attack  the 
tuber  between  the  cuticle  and  spiral  vessels. 

4.  Section  of  a  potatoe  affected  with  dry  gangrene,  with  a 
cavity  in  its  interior  of  the  form  of  an  irregular  X.     The  mass 
left  in  this  case  is  principally  starch.    (Natural  size.) 

5.  Section  of  parsnip  in  the  first  stage  of  the  disease.     (Na- 
tural size.) 

6.  Mangel  wurtzel.     In  this  case  the  whole  structure  ap- 
peared killed,  and  the  malady  is  seen  to  progress  from  the  spiral 
vessels.     (Natural  size.) 

7.  Cells  of  diseased  potatoe  empty  of  starch.     (Magnified.) 

8.  A  section  of  healthy  wild  potatoe,  showing  the  cells  filled 
with  starch.     (Magnified.) 

9.  Starch  with  cellular  tissue  disorganized,  and  fungoid  fibre 
substituted.     (Magnified.) 

10.  Little  aggregations  of  starch,  which  are  to  be  seen  occa. 
sionally  in  diseased  potates  in  little  isolated  masses.  (Magnified.) 

PLATE  VIII. 

APHIS  VASTATOR. 
All  the  figures  are  magnified. 

FIG.  1.  The  ovum  immediately  after  exclusion,  showing  the 
two  eyes  through  the  membrane. 

2.  Young  Aphis. 

3.  Full-grown  larva,  with  the  antennae  in  the  position  it  car- 
ries them  when  on  the  march. 

4.  Aphis  vastalor  in  the  pupa  state.     In  this  figure  the  anten- 
nae are  reflexed  over  the  back,  a  position  which  the  insect  always 
takes  when  feeding. 

5.  Claw  of  the  Aphis. 

6.  Abdominal  tubercle. 

7.  Rostrum. 


XXIV  EXPLANATION    OF    THK    PLATES. 

a  Setae  withdrawn.  b  the  setae  projecting. 

c  Seise  separated  into  three  parts,  the  outer  of  which  correspond  to  the  jaws 
of  insects,  the  middle  one  to  the  tongue.  It  is  by  this  apparatus  the  insect  pierces 
the  cells  of  the  plant,  which  enables  it  to  suck  the  juices. 

PLATE  IX. 

APHIS   VASTATOR. 
All  the  figures  are  magnified  except  the  leaflet. 

FIG.  1.  Aphis  vastalor  in  the  winged  state. 

2.  Under  side  with  rostrum  in  situ. 

3.  One  of  the  antennae  carefully  drawn  with  the  camera  lu- 
cida. 

4.  Perfect  insect,  showing  the  manner  in  which  it  carries  its 
wings  in  a  state  of  repose. 

5.  Aphis  vastator  in  which  an  ichneumon  had  deposited  its 
eggs,  and  from  which  the  perfect  parasite  has  escaped  through 
the  aperture  shown  in  the  dorsum. 

6.  Leaflet  (natural  size),  showing  its  appearance  when  co- 
vered by  the  vastator.     For   perspicuity  the   antennas  are  all 
shown  projecting  in  front,  whilst  in  reality  they  are  reflexed  when 
the  insect  is  feeding. 

PLATE   X. 

DESTROYERS   OF   APHIDES. 

FIG.  1.  Psen  equestris. 

2.  Diodontis  gracilis. 

3.  Cynips. 

4.  Aphidius  rapae. 

5.  Larva  of  Chrysopa  perla. 

6.  Chrysopa  perla. 

7.  Larva  of  Scaeva  pyrastri. 

8.  Pupa  of  Scaeva  pyrastri. 

9.  Scaeva  pyrastri. 

10.  Larva  of  a  Coccinella. 


EXPLANATION  OF  THE  PLATES.          XXV 

11.  Coccinella  punctata. 

12.  Coccinella  instabilis, 

13.  Pemphredon  unicolor. 

14.  Colax  dispar. 

15.  Tropoxylon  clavicerum. 

The  genera,  Nos.  1,2,  13,  and  15,  deposit  the  Aphides  in  the 
cells  with  their  eggs,  to  feed  their  larvae  when  they  are  hatched. 

It  is  probable  that  many  more  of  the  fossorial  Hymenoptera 
furnish  their  cells  with  Aphides,  as  food  for  their  young;  and  the 
insects  figured  are  rather  to  illustrate  the  genera  that  prey  upon 
Aphides,  than  the  species  that  specially  destroy  the  vastator. 

Nos.  3  and  4  deposit  their  eggs  in  the  Aphides. 

Nos.  5, 7,  10, 11,  and  12,  feed  upon  the  Aphides. 

No.  15  is  parasitic  upon  some  of  the  parasites  of  Aphides. 


INTRODUCTION. 


A  VERY  bad  disease  now  exists  in  the  potatoe  plant, 
but  it  is  by  no  means  certain  at  what  period  the  ma- 
lady first  appeared.  The  first  description,  of  any 
importance,  of  the  present  epidemic,  is  (as  far  as  I 
can  learn)  to  be  found  in  a  treatise  by  Von  Martius, 
who  conceives  that  the  disease  is  attributable  to  ve- 
getable fungi. 

Martius  states  that  the  disease  has  existed  in  Ger- 
many since  the  year  1830,  and  that,  in  November  of 
the  year  1841,  Dr.  Zuchcariani  wrote  a  paper  upon 
the  disease,  which  was  read  in  the  Royal  Bavarian 
Academy  of  Arts.  In  1^40  the  malady  spread  ra- 
pidly through  the  Bavarian  Palatinate,  which  caused 
inquiry.  On  the  27th  February,  1842,  the  Govern- 
ment issued  an  order  for  the  Academy  to  inquire 
into  the  malady,  and  transmitted  to  them  various 
samples  of  the  diseased  tuber.  At  that  time  Zuch- 
cariani was  indisposed,  and  on  this  account  Von 
Martius  undertook  the  investigation. 

In  this  country,  Dr.  Bell  Salter,  on  August  16th, 
1845,  first  communicated  to  the  "  Gardener's  Chro- 
nicle" the  startling  intelligence,  that  a  blight  of  an 


XXV111  INTRODUCTION. 

universal  character  had  appeared  in  the  potatoe  plant; 
which  intelligence  was  speedily  confirmed  by  other 
observers.  When  the  fact  was  announced,  several 
communications  were  sent,  to  the  effect  that  the  dis- 
ease had  existed  to  a  large  extent  the  previous  sea- 
son ;  but,  strangely  enough,  although  the  fact  is 
undoubted,  no  person  had  chronicled  the  important 
circumstance. 

Every  circumstance  worthy  of  note  upon  this  all- 
interesting  topic  is  to  be  found  in  the  daily  and  weekly 
newspapers  ;  and  now,  scientific  intelligence  is  so 
rapidly  promulgated  in  these  great  organs  of  know- 
ledge, that  an  invention  of  one  day  is  in  active  ope- 
ration over  the  country  the  next.  This  extraordinary 
and  rapid  diffusion  of  knowledge  is  certainly  not 
without  its  disadvantage  ;  for  though  it  be  communi- 
cated with  great  rapidity,  yet  the  subsequent  refer- 
ence to  it  is  the  less  easy,  as  the  mass  of  newspapers 
is  so  great,  that  it  is  almost  impossible  to  hunt  over 
by-gone  periodicals  for  particular  essays. 

The  "  Gardener's  Chronicle,"  under  the  able  editor- 
ship of  Dr.  Lindley,  has  always  freely  discussed  the 
subject  since  the  16th  of  August,  1845.  In  the 
"  Illustrated  London  News  "  there  is  also  an  excel- 
lent article,  illustrated  by  wood  cuts,  which,  if  we  can 
believe  common  report,  was  also  written  under  the 
superintendence  of  the  same  distinguished  botanist. 

If  we  turn  to  the  proceedings  of  the  great  learned 
societies,  we  shall  perceive  that  they  have  not  done 
much  for  the  inquiry.  The  Royal  Society  contains 


INTRODUCTION.  XXIX 

a  large  number  of  the  most  distinguished  and  active 
men  in  their  private  capacity  in  Europe  ;  yet,  col- 
lectively, they*  are  inactive,  and  a  century  behind  the 
spirit  of  the  age.  Their  Transactions  are  published 
but  twice  a  year,  whilst  a  discovery  in  these  days 
has  its  run,  and  is  supplanted  by  another  discovery, 
in  half  that  time.* 

All  the  minor  societies,  also,  which  have  split  from 
the  great  parent  institution,  for  the  advancement  of 
natural  knowledge,  partake  of  its  inactive  character, 
and  have  made  scarcely  any  attempt  to  elucidate  the 
nature  of  the  present  malady. 

In  the  year  1845  Commissioners  were  appointed 
by  Government  to  inquire  into  the  present  malady 
existing  in  the  potatoe  plant ;  and  three  able  men, 
Kane,  Lindley,  and  Play  fair,  were  selected  to  per- 
form these  duties.  As  far  as  their  investigations  went, 
their  recommendations  were  practical  and  generally 
valuable.  Their  attention,  however,  at  that  time, 
was  properly  concentrated  on  the  best  mode  of  pre- 
serving the  tuber,  instead  of  ascertaining  the  cause 
of  the  malady. 

The  investigation  into  the  nature  of  an  universal 
disease  among  organic  bodies  belongs  especially  to 
the  practical  surgeon.  He  is  investigating  disease  in 
every  hour  of  the  day,  and  every  day  of  his  life.  He 

*  This  year  forms  an  exception  to  the  general  rule,  as  four  parts 
have  been  published  at  a  cost  exceeding  1000/. ;  but  no  doubt  a 
more  frequent  and  cheaper  means  of  publication  might  be  em- 
ployed. 


XXX  INTRODUCTION. 

is  accustomed  to  weigh  the  various  difficulties  which 
arise  in  the  investigation  of  a  complex  organic  body ; 
and  on  that  account  he  is  peculiarly  suited  for  the 
discovery  of  the  cause  of  an  universal  malady.  The 
disease  in  the  plant  is  a  death  of  the  vegetable  tissue, 
and  the  questions  of  life  and  death  especially  pertain 
to  the  business  of  a  surgeon. 

The  death  of  a  vegetable  is  referable  to  causes 
precisely  similar  to  those  which  occasion  the  death  of 
an  animal  ;  and  although  the  embarrassing  circum- 
stances are  less  numerous  in  the  vegetable  than  in 
the  animal,  yet  they  are  of  the  same  nature,  and  are 
to  be  investigated  upon  similar  principles.  It  is  for 
this  reason  that  I  attempted  the  inquiry,  and  I  applied 
a  mode  of  investigation  into  the  cause  of  the  potatoe 
disease,  similar  to  that  which  I  should  have  employed 
in  an  investigation  of  the  causes  of  death  in  the  hu- 
man being,  and  the  result  has  been  the  elucidation  of 
the  mystery. 

Man  is  influenced  by  temperature,  light,  electricity* 
barometric  pressure,  hygrometric  state  of  atmosphere ; 
by  the  action  of  new  material  as  food,  morbid  poisons, 
air  for  respiration  ;  by  anything  which  draws  nour- 
ishment from  the  body  ;  by  vegetable  parasites,  as  in 
the  case  of  scald-head ;  by  animal  parasites,  as  in  the 
case  of  tape- worm,  pediculi,  &c.  ;  and,  last  of  all,  he 
is  influenced  by  moral  impressions,  as  fear,  hope,  joy, 
&c.  The  vegetable  is  influenced  in  a  similar  man- 
ner by  temperature,  light,  electricity,  barometric 
pressure,  hygrometric  state  of  atmosphere ;  by  the 


INTRODUCTION.  XXXI 

action  of  new  matter,  such  as  manures,  the  carbonic 
acid  in  the  atmosphere,  poisonous  agents  ;  by  any 
circumstance  'which  draws  matter  from  its  texture  ; 
by  vegetable  parasites,  and  animal  parasites.  In  all 
these  respects  the  pathology  of  the  vegetable  is  like 
the  pathology  of  the  animal,  except  that  it  is  less 
complex,  and  presents  fewer  difficulties  to  investiga- 
tion. 

The  business  of  a  surgeon  is  essentially  locomotive, 
and  his  duties  are  practised  over  an  extensive  space. 
It  frequently  happens  that  I  have  to  traverse  Lon- 
don in  two  or  even  more  directions  in  a  single  day, 
which  circumstance  has  given  me  abundant  oppor- 
tunities of  making  my  observations  in  different  lo- 
calities. 

Moreover,  during  the  summer  months,  I  was  living 
at  Springfield,  Upper  Clapton,  where  I  had  the  ad- 
vantage of  a  large  garden,  wherein  were  several 
plots  of  potatoes,  which  I  was  in  the  habit  of  observ- 
ing th^  first  thing  in  the  morning,  again  on  my  return 
from  London,  and  frequently  the  last  thing  at  night. 
In  the  neighborhood,  moreover,  were  larger  potatoe 
grounds,  where  I  used  to  enjoy  the  air,  and  study  the 
disease  in  the  evening  ;  and  it  has  curiously  happened, 
that  I  have  made  my  observations  on  the  potatoe 
plant  in  the  same  garden  in  which  I  conducted  the 
experiments  for  my  former  work,  on  "  Electro-Metal- 
lurgy." 

I  must  caution  my  readers  against  supposing  that 
they  will  be  able  to  find  in  a  single  day  all  the 


XXX11  INTRODUCTION. 

evidence  which  I  have  collected.  They  will  have  to 
traverse,  as  I  have  done,  many  miles  to  procure  it, 
especially  with  relation  to  its  existence  in  the  rarer 
plants.  It '  is  only  where  the  insect  excessively 
abounds  that  many  of  the  plants  are  affected  ;  and  so 
numerous  are  the  creatures  sometimes,  that  I  have 
taken  a  lid  of  a  pill-box,  and  scooped  up  half  a  box 
full  of  the  winged  creatures  from  a  single  leaf  of  the 
beet  plant.  Their  number  in  some  cases  has  ex- 
ceeded all  description ;  and  there  was  a  little  field  in 
the  Old  Kent  Road,  surrounded  by  houses,  which 
presented  a  wonderful  living  mass  of  these  creatures. 

The  migratory  habits  of  the  insect  will  sometimes 
perplex  the  investigator  ;  for,  upon  searching  over  a 
tract  of  land,  he  may  find  none  of  these  creatures  ; 
yet,  upon  a  more  careful  scrutiny,  the  ichneumoned 
remains  which  are  still  to  be  seen  adhering  to  the 
leaf,  will  benr  sufficient  testimony  of  the  previous 
existence  of  the  destroyer. 

The  examination  of  the  plants  for  the  Vastator 
may  be  performed  with  the  naked  eye,  though  the 
more  minute  investigation  of  the  insect  itself  doubt- 
less requires  a  glass.  The  agriculturist  should  pro- 
cure a  small  pocket  glass,  with  lenses  of  three  focal 
distances,  which  he  can  procure  for  five  shillings. 

He  should  also  possess  a  microscope  of  higher 
power,  to  examine  more  minutely  the  parts  of  insects. 
These  can  be  bought  for  twenty-five  shillings,  but 
I  should  certainly  recommend  him  not  to  give  less 
than  five  guineas  for  an  instrument.  I  have  carefully 


INTRODUCTION. 


XXX111 


examined  a  microscope  which  is  manufactured  at 
that  price  by  Messrs.  Home,  of  Newgate-street, 
which  he  calls  the  "  medical  microscope."  The  me- 
chanical part  is  strong  and  steady,  and  the  rack-work 
excellent.  It  possesses  a  good  achromatic  object- 
glass,  which  can  be  used  of  three  powers,  and  is  am- 
ply sufficient  to  examine  the  structure  of  the  potatoe, 
the  various  fungi,  and  the  form  of  the  insect.  When 
circumstances  will  admit,  he  may  extend  the  cost  of 
the  apparatus  to  100  guineas  ;  but  the  five  guinea 
instrument,  except  for  very  difficult  cases  of  original 
research,  will  answer  all  or  most  purposes. 

This  instrument  is 
represented  in  the 
engraving  set  up 
ready  for  use ;  and 
consists  of  a  firm 
brass  foot  (A),  into 
which  is  screwed 
the  pillar  (B), having 
*at  the  upper  part  a 
fine  rack-work  for 
adjusting  the  focus. 
At  the  top  of  the 
.pillar  is  a  brass  arm 
(C),  holding  the  body 
of  the  microscope 
(D),  consisting  of  a 
brass  tube,  in  the 
upper  part  of  which  slides  the  eye-piece,  so  that  it 


XXXIV  INTRODUCTION. 

may  occasionally  be  withdrawn  for  the  purpose  of 
cleaning  the  glasses,  which  is  best  done  with  a  piece 
of  soft  wash-leather  ;  the  lower  end  of  the  body  (D) 
has  a  screw,  to  which  is  attached  the  achromatic  ob- 
ject-glass (E).  The  object-glass  consists  of  three 
distinct  achromatic  lenses  of  equal  foci,  mounted  in 
brass  cells,  so  that,  one  or  more  can  be  used  at  the 
same  time,  according  to  the  power  required  :  for  ex- 
ample, if  the  whole  of  a  large  object  is  required  to 
be  seen  at  one  view,  a  single  achromatic  must  be 
employed,  but  if  only  a  particular  part  is  desired  to 
be  examined  with  a  high  power,  then  two  or  three 
•must  be  used  combined.  The  object  to  be  examined 
is  placed  on  the  concave  piece  of  glass,  which  fits 
the  aperture  of  the  stage  (F),  or  else  on  a  flat  strip 
of  glass,  which  is  retained  in  its  proper  position  by 
being  placed  beneath  the  brass  fork  (G)".  The  sil- 
vered concave  mirror  (H)  must  be  so  arranged  that 
a  strong  light  from  the  sky,  or  from  a  lamp  or  can- 
dle placed  about  eighteen  inches  from  the  mirror,  is 
reflected  through  the  axis  of  the  microscope. 

Whenever  I  found  a  plant  infested  by  an  Aphis 
which  appeared  to  be  the  vastator,  I  secured  speci- 
mens of  it  in  a  pill-box,  and  in  the  evening  placed 
it  in  Canada  balsam,  and  examined  it  more  carefully- 
In  this  way  I  have  preserved  all  my  evidences  upon 
this  point  for  future  reference  ;  and  as  the  name  of 
the  plant  on  which  the  insect  fed  was  immediately 
scratched  on  the  glass  with  a  diamond,  no  source  of 
error  could  possibly  arise. 


INTRODUCTION.  XXXV 

The  mode  of  fixing  the  insect  in  Canada  balsam 
is  very  simple :  a  slip  of  glass  is  warmed  over  a 
candle,  and  a  drop  of  the  balsam  is  then  placed  upon 
it ;  the  insect,  whilst  yet  alive,  is  placed  on  the  bal- 
sam, and  the  glass  is  then  again  very  gently  warmed, 
in  order  to  kill  the  insect ;  another  piece  of  the  glass 
is  then  heated  over  a  candle,  and  placed  on  the  in- 
sect, when  the  creature  will  be  hermetically  sealed 
up  for  ever.  It  is  necessary  that  the  insect  should  be 
dry  when  it  is  mounted,  and  we  must  take  especial 
care  not  to  apply  too  much  heat,  which  will  corrugate 
the  antennae,  and  destroy  the  form  of  the  insect. 

The  strips  of  thick,  and  pieces  of  thin  glass,  I 
always  procured  of  Mr.  Topping,  No.  1,  Penton- 
place,  Pentonville-hill,  who  is  moderate  in  his  charges 
and  exceedingly  obliging. 

I  strongly  recommend  to  all  entomologists  this 
mode  of  preserving  small  insects,  and  having  once 
properly  secured  them,  they  will  last  for  an  indefi- 
nite period,  and  can  be  handled  without  the  slightest 
risk  of  injury. 

It  is  admitted  on  all  hands  that  the  disease  in  the 
potatoe  plant  itself  is  a  local  or  general  death.  Now 
the  death  of  a  plant  may  arise  from  ten  thousand 
causes,  independently  of  the  present  cause,  which  is 
effecting  the  total  destruction  of  the  potatoe  plant 
Under  these  circumstances,  in  conducting  our  inves- 
tigations, we  must  isolate  solitary  causes  of  death 
and  confine  our  attention  to  the  particular  agent  which 
so  universally  affects  the  potatoe  plant.  A  plant  may 


XXX  VI  INTRODUCTION. 

die  from  heat,  from  cold,  from  light,  from  darkness, 
from  electricity,  from  moisture,  from  dryness,  from 
improper  soils.  We  isolate  all  these  causes  by  finding* 
that,  under  all  variations  of  their  influence,  the  disease 
more  or  less  appears ;  we  isolate  the  effects  of  vege- 
table fungi,  by  showing  that  they  do  not  appear  till 
the  plant  is  damaged. 

With  regard  to  animal  parasites,  we  discover  one 
particular  Aphis  which  comes  before  any  part  of  the 
plant  exhibits  the  malady.  But  here,  again,  in  the 
potatoe  plant,  we  have  other  sources  of  error.  A 
diseased  plant  propagates  its  disease  ;  hence  we  must 
prove  previous  health  before  we  can  show  that  the 
insect  comes  before  the  disease. 

We  then  look  about  other  plants,  and  find  that 
they  are  also  attacked  by  the  same  Aphis  ;  and  that 
when  they  are  so  attacked,  the  same  effects  are  mani- 
fested. The  mode  of  death  is  also  precisely  similar 
in  these  plants  to  that  in  the  potatoe  ;  for,  in  all  cases, 
the  collar  of  the  plant  becomes  swollen  with  watery 
matter  and  dies  ;  and  thus  the  root  is  separated  from 
the  leaf,  and  the  entire  plant  perishes. 

In  all  these  cases  the  vastator  is  the  antecedent, 
and  the  death  of  the  plant  the  consequent,  of  the 
malady.  We  desire  naturally  to  inquire  whether 
this  injurious  action  is  confined  to  one  species  of 
Aphis  ;  and  we  find  large  trees  destroyed,  and  other 
useful  crops  annihilated  by  other  species. 

Here  we  have  our  argument  strengthened  by  ana- 
logical cases  ;  but  we  are  naturally  led  to  inquire  why 


INTRODUCTION.  XXVII 

this  creature  should  do  this  mischief  particularly  at 
the  present  time  ;  and  the  answer  at  once  is,  that  there 
is  a  preternatural  abundance  of  these  creatures.  If  we 
search  historical  records,  we  find  that  insects  are  very 
prone  to  assume  these  periodic  multitudinous  appear- 
ances ;  and  what  is  most  strange  is,  that  they  almost 
totally  disappear  between  the  times  of  their  occur- 
rence. 

All  these  facts  I  have  fully  described,  and  have 
thus  proved  unquestionably  and  beyond  a  doubt  that 
the  vastator  is  the  cause  of  the  present  disease  in  the 
potatoe  plant ;  that  it  is  also  the  cause  of  the  present 
disease  amongst  various  other  plants ;  that  it  is  like 
all  other  Aphides  in  its  destructive  character ;  and, 
lastly,  that  the  preternatural  appearance  of  insects 
is,  and  has  been,  a  common  and  universally  known 
fact  from  the  earliest  ages. 


J 


PI.  2. 


GRATACAfjOr 


THE    POTATO  E, 

ITS    USES    AND    PROPERTIES. 

CHAPTER  I. 

ON    THE    POTATOE    PLANT. 

Parts  of  Potatoe  plant  (1) ;  set  (2) ;  stalk  (3). — Under -ground 
stem  and  tuber  (5-7) ;  roots  (8)  ;  haulm  (9)  ;  flowers  and  fruit 
(10). — Essential  parts  of  plants  (11,  12). — Ultimate  parts  of  pota- 
toes (13-16). — Origin  of  starch  (17). — Origin  of  nitrogen  (18).— 
Motion  of  sap  (19,  20). — Experiments  on  Endosmosis  (21). — 
Quantity  of  water  imbibed  by  roots  (22). — Resume  (23). 

(1.)  THE  perfect  potatoe  plant  (plate  11.,  fig.  1)  consists 
of  a  set,  or  original  potatoe,  under-ground  stem,  tubers, 
roots,  above-ground  stem,  leaves,  flowers,  and  fruit. 

(2.)  The  set,  or  original  potatoe  plant,  from  whence  the 
rest  of  the  plant  proceeds,  is  derived  from  a  former  plant, 
this  from  one  antecedent,  and  in  this  manner  we  might 
trace  it  up  to  the  first  potatoe  which  existed  on  the  earth's 
surface.  There  is  no  occasion  to  suppose  that  a  potatoe 
plant  has  had  in  all  cases  such  an  extensive  existence,  for 
we  may  trace  the  set  to  a  former  plant,  and  that  former 
plant  may  have  been  derived  from  the  potatoe-seed,  which 
I  shall  hereafter  more  fully  describe. 

1 


A  ON    THE    POTATOE    PLANT. 

(3.)  From  this  set,  or  original  potatoe,  a  stalk  or  stem 
proceeds,  which  takes  its  course  towards  the  light,  and 
becomes  the  haulm  or  stalk  of  the  plant.  The  stalk  pro- 
ceeds from  that  part  of  the  set  called  the  eye,  which  is  to 
the  potatoe  what  a  bud  is  to  a  tree.  From  a  potatoe  three 
or  more  large  stalks  will  grow;  and,  if  these  are  successively 
removed  and  separately  planted,  the  number  of  plants 
which  one  potatoe  will  produce  is  almost  incredible. 

(4.)  In  consequence  of  the  set  being  usually  below  the 
ground,  and  the  shoots  having  a  tendency  to  grow  towards 
the  light,  part  must  be  below  the  earth's  surface,  whilst  the 
other  part  extends  upwards  and  expands  its  foliage  to  the 
atmosphere. 

(5.)  From  that  part  below  the  earth's  surface  other 
stems  proceed,  which  are  termed  under-ground  stems, 
though  perhaps  they  should  rather  be  called  the  tuberose 
stems,  because  it  is  upon  these  that  the  tubers  or  potatoes 
are  found. 

(6.)  These  tuber-bearing  stems,  starting  from  the  main 
stem,  become  dilated  at  certain  intervals,  which  dilatation 
is  the  potatoe.  This  has,  at  certain  parts,  eyes  or  buds, 
from  whence  the  new  plant  grows. 

(7.)  From  the  potatoe  the  stem  extends  itself,  and  creep- 
ing upwards  through  the  ground,  at  last  becomes  a  stalk 
or  above-ground  stem,  sending  off  in  its  turn  other  tuber- 
bearing  stems  below  the  surface  of  the  ground,  and  hav- 
ing on  its  upper  part  foliage,  as  in  the  case  of  the  primary 
stem. 

(8.)  The  original  stem,  together  with  the  primary  and 
secondary  tuber-bearing  stems,  has  fine  filaments  running 
from  it  in  the  ground,  which  are  the  true  roots  of  the 
plant,  performing  the  same  functions  as  the  roots  of  other 


ON    THE    POTATOE    PLANT.  3 

plants,   and   which    are  totally  distinct   from   the  under- 
ground  stem. 

(9.)  The  stalk  or  haulm  divides  into  branches,  and  to 
these  the  leaves  are  attached.  The  leaves  themselves  con- 
sist of  a  series  of  leaflets,  each  leaflet  being  attached  by  a 
fine  stalk  to  the  main  stalk  of  the  leaf;  and  at  the  axil  of 
each  leaf  is  a  bud,  from  whence  the  potatoe  plant  may  be 
propagated  as  well  as  from  the  eye  of  a  tuber.  Sometimes 
a  potatoe  or  tuber  is  developed  at  the  axil  of  the  leaf. 

(10.)  Besides  these  various  parts,  the  plant  sends  forth 
flowers  which  in  time  produce  fruit,  and  this  fruit  is  termed 
the  potatoe  apple.  The  potatoe  apple  consists  of  a  pulpy 
envelope  containing  small  seeds,  from  which  also  plants 
may  be  raised. 

(11.)  Such  are  the  parts  of  which  the  potatoe  plant  is 
made  up  in  reality.  However,  we  might  consider  the 
plant  in  a  more  simple  manner,  for  its  only  essential  parts 
are  the  leaves  and  roots,  with  the  intervening  stems.  The 
tubers  are  mere  dilatations  of  the  stem,  and  the  flowers 
and  fruit  are  the  result  of  certain  conditions  of  the  plant, 
and  are  destined  to  perform  the  offices  of  reproduction. 

(12.)  Regarding  a  plant  in  this  point  of  view,  we  have 
an  organic  body  with  certain  parts  bearing  definite  relation 
to  each  other.  The  root  takes  up  moisture  and  earthy 
salts  from  the  ground;  the  leaves  separate  carbon,  and 
send  back  woody  fibre  to  the  root. 

(13.)  The  potatoe  plant,  like  all  organic  bodies,  con- 
sists of  a  solid  and  a  fluid  portion.  The  solid  portion  gives 
form,  tenacity,  and  firmness  to  the  plant,  and  is  composed 
of  matter  arranged  in  the  form  of  cells,  and  is  hence  called 
cellular  tissue. 

(14.)  These  cells  contain  the  fluid,  or  sap,  which,  when 


4  ON    THE    POTATOE   PLANT. 

influenced  by  the  external  agency  of  heat,  light,  and  elec- 
tricity, undergoes  various  changes  essential  to  the  vitality 
of  the  plant. 

(15.)  These  changes  can  only  take  place  when  the  sap 
is  in  proper  relation  to  the  cellular  tissue,  and  both  are 
acted  upon  in  a  proper  manner  by  heat  and  light.  Upon 
these  changes  depends  the  life  of  the  plant ;  and  the  moment 
these  changes,  from  any  cause,  cease,  other  changes, 
those  of  putrefaction,  ensue ;  the  plant  loses  its  organic 
existence,  and  is  obedient  to  the  laws  which  govern  inor- 
ganic bodies. 

(16.)  Perhaps  one  of  the  most  curious  facts  connected 
with  vegetable  physiology  is,  that  a  whole  plant  must  not 
be  subjected  equally  to  these  external  forces — one  part 
must  be  subjected  to  the  light  more  than  another ;  and 
this  singular  circumstance  gives  us  the  idea  of  a  root  and 
leaf,  the  one  creeping  into  dark  and  moist  recesses,  and 
the  other  seeking  the  all-important  influence  of  the  sun's 
rays. 

(17.)  The  starch  deposited  in  the  dilated  stem  or  tuber, 
is,  doubtless,  produced  by  the  leaves,  and  acts  as  a  source 
or  store-house  of  nutrition,  from  which  future  fibre  may  be 
formed.  It  is  not  itself  to  be  regarded  as  a  perfect  mate- 
rial, but  as  a  temporary  substance  deposited  for  the  future 
exigences  of  the  plant. 

(18.)  The  mode  in  which  plants  procure  their  nitrogen- 
ized  substance,  or  albumen,  does  not  appear  quite  clear. 
It  is  possible  that  the  nitrogen  may  become  fixed  from  the 
air,  or  it  is  possible  that  it  may  be  derived  from  the  earth 
in  which  the  plant  grows. 

(19.)  The  mechanism  whereby  the  fluid  rises  and  the 
solid  part  descends,  is  not  certainly  ascertained ;  eventually, 


ON   THE    POTATOE   PLANT.  O 

probably,  we  shall  find  that  it  is  due  to  some  very  simple 
law.  The  phenomena  of  endosmosis  may  explain  many 
of  the  facts  which  we  observe. 

(20.)  Various  theories  have  been  propounded  with 
respect  to  the  cause  of  the  motion  of  the  sap,  but  a  very 
simple  experiment  will  show  how  water  may  be  taken  from 
the  earth,  and  how  the  solid  material  may  be  sent  back  to 
the  root  through  the  same  vessel,  and  in  fact  how  both 
operations  may  proceed  at  one  time. 

(21.)  To  explain  this  phenomenon,  take  a  tube  having  a 
rim  at  one  end,  and  tie  a  piece  of  goldbeater's  skin  over 
the  rim.  Into  this  tube  put  a  solution  of  chloride  of  cal- 
cium, sugar,  or  indeed  of  almost  any  body  which  will  add 
to  the  specific  gravity  of  the  fluid,  and  then  immerse  the 
tube  in  a  glass  of  pure  water.  After  a  short  time  the  wa- 
ter will  pass  into  the  tube,  and  at  last  run  over  like  the 
bleeding  haulm.  The  leaf  may  be  imitated  by  a  piece  of 
blotting  paper ;  and  it  is  possible  exactly  to  regulate  the 
amount  of  attraction  to  the  evaporation.  The  descent  of 
the  salt  or  sugar,  like  that  of  the  solid  material  descending 
from  the  leaf,  may  be  proved  by  examining  the  glass  of 
water,  when  it  will  be  found  that  the  solid  matter  has  de- 
scended, in  spite  of  the  powerful  ascending  current  which 
is  opposed  to  the  force  of  gravitation. 

(22.)  To  show  the  extent  to  which  the  potatoe  draws 
water  from  the  earth,  Marshall  states,  that,  "  on  observing 
the  place  where  the  haulm  was  cut,  he  found  wet  places 
covered  with  vegetable  blood,  and  that  the  stems  bled  pro- 
fusely. On  examining  it  more  accurately  he  noticed  that 
each  stem  exhaled  seven  hundred  and  twenty  drops  in 
twenty-four  hours,  and  continued  for  about  seven  days, 
giving  off  in  drops  two  pints  and  a  half  of  liquid  in  that 


ON   THE    INDIVIDUALITY 

time.  Upon  this,  calculating  the  number  of  stems  in  one 
acre  of  land,  he  concluded  that  five  tons  of  liquid  were  ex- 
haled daily,  and  that  in  a  week  they  carried  into  the 
atmosphere  a  sheet  of  water  equal  to  their  own  superficies, 
and  one-third  of  an  inch  in  thickness. 

(23.)  Avoiding  theories,  I  desire  to  impress  upon  my 
readers  in  this  chapter,  that  a  root  and  a  leaf  are  required 
for  the  perfect  potatoe  plant,  and  that  these  two  parts  bear 
important  relation  to  each  other,  for  the  continuance  of  the 
vital  action  between  the  sap  and  cells. 


CHAPTER  II. 

INDIVIDUALITY  OF  THE  POTATOE  PLANT. 

Individuality  of  the  potatoe  plant  (24).— Plurality  of  individuals 
(25). — Individuals  are  seedlings  (26 — 29). — Duration  of  indivi- 
duals (30). — Potatoe  botanically  considered  (31). — Gerard's  de- 
scription (32 — 34).— Introduction  of  potatoe  (35,  36). — Wild 
potatoes  (37). — Humboldt's  account  (38,  39). — Meyer's  account 
(41).— Don  Jose  Pavon  (42).— Caldcleugh  (43— 46),— Chelsea 
wild  root  (47— 49).— Uhde  (50).— Origin  of  our  varieties  (51).— 
Number  of  (52). — Propagation  of  (53). — Selection  of  (54).— Ana- 
logies of  varieties  (55,  56). — Sweet  potatoe  (57 — 59). — Origin  of 
name  (60). — Resume  of  the  chapter  (61). 

(24.)  THE  potatoe  plant  which  I  have  described  is  an 
individual,  propagating  its  individuality  or  peculiarity 
from  potatoe  to  potatoe,  and  which  peculiarity  cannot  be 
materially  affected  by  external  agents.  If  we  propagate 
one  kind  of  potatoe  for  several  years,  it  still  remains  the 


OF    THE    POTATOE    PLANT.  7 

same  kind ;  and  although  millions  of  potatoes  have  been 
raised  from  theoriginal  parent  plant,  yet  the  millionth  potatoe 
is  but  an  extension  of  the  first  plant  of  that  peculiar  kind. 
(25.)  We  have,  however,  many  kinds  of  potatoes,  and, 
therefore,  many  individuals  which  we  have  preserved  and 
propagated,  because  their  individual  peculiarities  have  been 
found  to  be  most  serviceable  to  the  wants  of  man. 

(26.)  These  kinds  of  potatoes  are  seedlings,  and  each 
seedling  is  a  distinct  individual,  which,  although  it  may 
follow  the  general  law  of  the  transmission  of  peculiarities 
from  parent  to  offspring,  is  yet  always  liable,  after  a  few 
generations,  to  revert  to  the  original  type,  whence  all  the 
varieties  came. 

(27.)  When  persons  are  desirous  of  raising  new  kinds 
of  potatoes,  they  sow  seed  and  collect,  the  produce.  If  any 
one  plant  is  particularly  good  in  quality,  they  specially 
preserve  it ;  and  so  long  as  this  plant  is  propagated  by  the 
tubers,  the  distinctness  or  the  excellence  of  the  kind  is 
preserved. 

(28.)  When  you  are  desirous  to  raise  potatoes  from 
seed,  collect  the  apples  in  autumn  when  they  will  fall 
spontaneously  ;  preserve  them  in  sand  till  spring  ;  sow  in 
fine  garden  mould ;  transplant,  as  soon  as  the  young 
plants  are  strong  enough,  into  other  mould,  and  keep  clear 
from  weeds.  The  tubers  of  the  first  year  are  as  big  as 
a  nut  or  walnut ;  those  of  the  second  year  attain  a  middle 
size ;  and  in  the  third  or  fourth  full-sized  tubers  are  pro- 
duced. 

(29.)  This  mode  of  raising  choice  potatoes  is  similar  to 
that  of  raising  all  other  vegetable  varieties ;  for  the  deli- 
cious Ribston  pippin  is  but  a  seedling  variety  of  the  com- 


8  ON    THE    INDIVIDUALITY 

mon  crab  ;  and  the  large  strawberries  now  supplied  to  the 
London  market  are  but  seedlings  of  the  little  /Upine. 

(30.)  The  duration  of  the  life  of  an  individual  potatoe  is 
altogether  unknown,  for  it  is  uncertain  whether  a  single 
plant  is  capable  of  being  indefinitely  propagated,  or 
whether  after  a  certain  time  it  becomes  feeble,  and  ceases 
to  live  from  mere  old  age.  There  is  a  strong  feeling  gene- 
rally in  favor  of  this  latter  hypothesis  with  gardeners 
and  farmers. 

(31.)  The  potatoe  plant  belongs  to  the  nightshades,  or 
genus  Solanum,  and  is  called  botanically  the  Solarium  tu- 
berosum.  It  is  grouped  in  the  same  natural  family  with 
very  many  poisonous  plants,  such  as  the  tobacco,  belladon- 
na, stramonium,  henbane ;  aad  the  plant  itself  contains  a 
poisonous  ingredient,  which  I  shall  hereafter  describe. 

(32.)  The  first  figure  of  a  potatoe  is  to  be  found  in  Ge- 
rard, Herbal  (1597).  He  there  calls  it  Batata  Virginiana. 
He  states  that  "  the  root  is  thick,  fat,  tuberous,  not  much 
differing  in  shape,  color,  and  taste  from  the  common 
potatoe,  saving  that  the  roots  hereof  are  not  so  great  nor 
long  ;  some  of  them  are  as  a  ball,  some  oval  or  egg- fashion, 
some  larger,  some  shorter,  the  which  knobby  roots  are  fast- 
ened into  the  stalks  with  an  infinite  number  of  thready 
strings.  (Plate  1.) 

(33.)  "  It  groweth  naturally  in  America,  where  it  was 
first  discovered,  as  report  says,  by  Columbus,  since  which 
time  I  have  received  roots  hereof  from  Virginia,  otherwise 
called  Nurenbega,  which  grow  and  prosper  in  my  garden 
as  in  their  own  country. 

(34.)  "  The  Indians  do  call  this  plant  '  pappas/  meaning 
the  roots,  by  which  name  also  the  common  potatoes  are 
called  in  those  Indian  countries.  We  have  the  name 


OF    THE    POTATOE    PLANT.  9 

proper  to  it  mentioned  in  the  title,  because  it  hath  not  only 
the  shape  and  proportion  of  potatoes,  but  also  the  pleasant 
taste  and  virtues  of  the  same :  we  may  call  it  in  English, 
1  potatoes  of  America  or  Virginia.' ' 

(35.)  In  1693  Sir  Robert  Southwell  informed  the  Pel- 
lows  of  the  Royal  Society  that  his  grandfather  introduced 
potatoes  into  Ireland,  and  that  he  first  had  them  from  Sir 
W.  Raleigh.  He  probably,  however,  only  had  that  state- 
ment by  tradition,  and  therefore  I  attribute  very  little  value 
to  the  fact,  further  than  to  show  that  about  the  time  of  its 
introduction  it  was  commonly  supposed  to  have  come  from 
Virginia.  In  confirmation  of  this  statement,  we  must  not 
forget  that  Sir  Walter  Raleigh  gave  the  name  to  Virginia. 

(36.)  It  is  said  that  the  potatoe  was  also  imported  into 
Italy  about  the  same  period  from  South  America^  and 
Clusius  mentions  that  he  received  it  therefrom.  In  all 
probability,  the  Papists,  who  early  had  a  strong  footing  in 
that  quarter  of  the  globe,  transmitted  the  root  to  the  Pope. 
In  those  times  the  potatoe  was  esteemed  as  a  provocative 
to  lust. 

(37.)  The  potatoe  plant,  however,  does  not  grow 
wild  in  Virginia,  nor  in  any  part  of  North  America ;  but 
in  its  natural  state  is  only  to  be  found  on  the  western  side 
of  South  America. 

(38.)  Hurnboldt  states  that  "the  plants  which  are  culti- 
vated in  the  highest  and  coldest  part  of  the  Andes  and 
Mexican  Cordilleras  are  the  potatoes,  the  Tropwolum  escu- 
lentum  (page  448). 

(39.)  Humboldt  also  states  (page  441)  that  "the  pota- 
toe is  not  indigenous  in  Peru,  and  that  it  is  nowhere  to  be 
found  wild  in  the  part  of  the  Cordilleras  situated  under  the 
tropics.  M.  Bompland  and  myself  herborized  in  the  back 

1* 


10  ON    THE    INDIVIDUALITY 

and  in  the  declivity  of  the  Andes,  from  the  5°  north  to  the 
12°  south,  and  informed  ourselves  from  persons  who  have 
examined  this  chain  of  colossal  mountains  as  far  as  the  Le 
Pan  and  Oruro,  and  we  ascertained  that  in  this  vast  extent 
of  ground  no  species  of  solanum  with  nutritive  roots  vege- 
tates spontaneously.  It  is  true  that  there  are  places  not 
very  accessible,  and  very  cold,  which  the  natives  call 
'  Parana  de  las  Papas.'  '• 

(40.)  Passing  further  southward  beyond  the  tropics,  we 
find  that,  according  to  Molina,  in  the  fields  of  Chili,  the 
natives  distinguish  the  wild  potatoe,  of  which  the  tubers 
are  small  and  somewhat  bitter,  from  that  which  has  been 
cultivated  for  a  long  series  of  years. 

(41.)  Meyer  observes,  that  "if  the  potatoe  had  migrated 
from  Chili  to  Peru,  it  would  probably  have  retained  its 
Chilian  name ;  but  this  conjecture  is  no  longer  necessary, 
for  it  grows  wild  in  both  countries.  I  myself  have  found  it 
in  two  different  places  on  the  Cordilleras  of  these  countries." 
Jenin  and  Pavon  mention  the  mountain  of  Chancay  as  a 
station  where  the  potatoe  is  to  be  found  wild. 

(42.)  "Don  Jose  Pavon,  in  a  letter  to  M.  Lambert, 
says  that  Solanum  tuberosum  grows  wild  in  the  en- 
virons of  Lima,  and  fourteen  leagues  from  Lima  on  the 
coast;  and  I  myself  have  found  it  in  the  kingdom  of 
of  Chili.  And  M.  Lambert  adds,  '  I  have  lately  re- 
ceived from  M.  Pavon  very  fine  wild  specimens  of 
Solanum  tuberosum  collected  by  himself  in  Peru.  In 
Chili  it  is  generally  found  in  steep  rocky  places,  where  it 
could  never  have  been  cultivated,  and  where  its  introduc- 
tion must  have  been  almost  impossible.  It  is  very  com- 
mon about  Valparaiso,  and  Cruickshank  has  noticed  it 
along  the  coast  for  fifteen  leagues  to  the  northward  of  that 


OF   THE    POTATOE    PLANT.  11 

port ;  how  much  further  it  may  extend  north  or  south,  he 
knows  not.'  "* 

(43.)  Caldcleugh,  who  had  been  some  time  resident  at 
Rio  Janeiro,  holding  the  office  of  secretary  to  the  British 
minister,  brought  with  him  two  tubers  of  the  wild  potatoe, 
which  he  sent  to  the  secretary  of  the  Horticultural  Society 
of  London,  with  the  following  letter,  which  is  to  be  found 
at  p.  249  in  the  fifth  volume  of  the  Transactions  of  the 
Society. 

(44.)  "  '  It  is  with  no  small  degree  of  pleasure  that  I  am 
enabled  to  send  you  some  specimens  of  the  Solanum  tubt- 
rosum,  or  native  wild  potatoe  of  South  America.  It  is 
found  growing  in  considerable  quantities  in  ravines  in  the 
immediate  neighborhood  of  Valparaiso,  on  the  western  side 
of  South  America,  in  lat.  34^°  south.  The  leaves  and 
flowers  of  the  plant  are  similar  in  every  respect  to  those 
cultivated  in  England  and  elsewhere.  It  begins  to  flower 
in  the  month  of  October,  the  spring  of  that  climate,  and  is 
not  very  prolific.  The  roots  are  small,  and  of  a  bitterish 
taste,  some  with  red,  and  others  with  yellowish  skins,  I 
am  inclined  to  think  that  this  plant  grows  on  a  large  extent 
of  the  coast,  for  in  the  south  of  Chili  it  is  found,  and  is 
called  by  the  natives  maglia,  but  I  cannot  discover  that  it 
is  employed  to  any  purpose.  I  am  indebted  for  these 
specimens  to  an  officer  of  his  Majesty's  ship  Owen  Glen- 
dower,  who  left  the  country  some  time  after  me.' 

(45.)  "  The  two  tubers  were  exhibited  to  the  Society, 
and  a  drawing  made  of  them  before  they  were  planted 
(plate  ix.,  fig.  2,  Hort.  Trans.,  vol.  5).  Had  there  been 
a  third,  I  should  have  been  tempted  to  have  satisfied  my- 

*  Hooker's  Botanical  Miscellany,  as  quoted  in  the  Journal  of  the 
Royal  Institution,  1831. 


12  ON    THE    INDIVIDUALITY 

self  as  to  the  real  flavor  which  Mr.  Caldcleugh,  as  well  as 
Molina,  describes  as  bitter.  They  were  planted  separate- 
ly in  small  pots,  and  speedily  vegetated  ;  they  grew 
rapidly,  and  were  subsequently  turned  out  into  a  border  at 
about  two  feet  distance  from  each  other,  when  they  be- 
came very  strong  and  luxuriant.  The  blossoms  at  first 
were  but  sparingly  produced,  but  as  the  plants  were 
earthed  up  they  increased  in  vigor,  and  then  bore  flowers 
abundantly ;  but  these  were  not  succeeded  by  fruit.  A 
drawing  of  a  branch  was  made  by  Miss  Cotton,  which  has 
been  engraved  (plate  xii.,  Hort.  Trans.,  vol.  5).  The 
flower  was  white,  and  differed  in  no  respect  from  those 
varieties  of  the  common  potatoe  which  have  white 
blossoms.  The  leaves  were  compared  with  specimens  of 
several  varieties  of  the  cultivated  potatoe,  which  generally 
were  rather  more  of  a  rugose  and  uneven  surface  above, 
and  with  the  veins  stronger  and  more  conspicuous  below, 
but  in  other  respects  there  was  no  difference  between 
them.  The  pinnulae,  which  grew  on  the  sides  of  the 
petiole,  between  the  pinnae  of  the  leaves,  were  few,  not 
near  so  numerous  as  in  some  varieties  of  the  cultivated 
potatoe  j  but  in  specimens  of  other  varieties  that  were 
examined,  their  leaves  were  destitute  of  pinnulae,  so  that 
the  existence  of  these  appendages  does  not  appear  to  be  so 
essential  a  characteristic  as  has  been  supposed,  and  as  is 
stated  in  the  supplement  to  the  '  Encyclopaedia.' 

"  The  plants  have  been  recently  taken  up,  and  all  doubt 
respecting  them  is  now  removed  ;  they  are  unquestionably 
the  Solanum  tuberosum.  The  principal  stems,  when  ex- 
tended, measured  more  than  seven  feet  in  length.  The 
produce  was  most  abundant ;  above  six  hundred  tubers 
were  gathered  from  the  two  plants.  They  are  of  various 


OF    THE    POTATOE    PLANT.  13 

sizes,  a  few  as  large  or  larger  than  a  pigeon's  egg,  others 
as  small  as  the  original  ones,  rather  angular,  but  more 
globular  than  oblong ;  some  are  white,  others  marked  with 
blotches  of  pale  red  or  white ;  two  of  these  were  selected 
to  be  drawn,  and  are  represented  (plate  ix.,  fig.  3,  Hort. 
Trans.,  vol.  5).  The  flavor  of  them  when  boiled  was 
exactly  that  of  a  young  potatoe. 

"  The  compost  used  in  moulding  up  the  plants  was  very 
much  saturated  with  manure,  and  to  this  circumstance  I 
attribute  the  excessive  luxuriance  of  the  growth  of  the 
stems.  Had  common  garden  mould  been  applied,  they 
would  not  probably  have  grown  so  strong  ;  and  I  suppose, 
that  whilst  the  plants  were  thus  rapidly  making  stems  and 
leaves,  the  formation  of  the  tubers  was  delayed,  for  the 
production  of  these  has  been  the  work  of  the  latter  part  of 
the  season.  They  cannot  be  called  fully  ripe,  nor  have 
they  attained  the  size  which  they  probably  might  have 
done  if  they  had  been  formed  earlier." 

(46.)  I  am  informed  by  Mr.  Thompson  that  this  wild 
potatoe  was  lost  from  the  Horticultural  Gardens  many 
years  ago. 

(47.)  There  is,  at  the  Botanical  Gardens,  Chelsea,  a 
fine  plant,  said  to  be  of  the  wild  potatoe,  which  Mr.  An- 
derson informs  me  he  obtained  from  Mr.  Renegal,  who 
procured  it,  together  with  some  nasturtiums,  from  Santa 
Fe. 

(48.)  This  plant  has  been  in  the  garden  about  ten  years, 
and  bears  tubers  of  a  medium  size,  of  a  mottled  white  and 
red  color.  When  cooked  they  have  a  high  flavor,  and 
are  perhaps  a  little  bitter :  in  other  respects  they  some- 
what resemble  the  new  tubers  of  ordinary  potatoes.  When 
the  plant  was  removed  from  the  ground,  its  total  length 


14  ON    THE    INDIVIDUALITY 

from  the  top  of  the  stem  to  the  end  of  the  root  was  about 
eight  feet.  In  this  instance  the  amount  of  tubers  was  very 
small  relatively  to  the  size  of  the  leaf,  when  compared 
with  plants  of  other  varieties. 

(49.)  This  plant  was  characterized  not  only  by  this 
abundance  of  leaves,  but  was  peculiar  also,  in  having  a 
great  tendency  to  send  forth  numerous  lateral  shoots  at  the 
surface  of  the  ground,  which,  spreading  in  all  directions, 
become  other  above-ground  stems. 

(50.)  Another  wild  plant  has  been  received  by  the 
Horticultural  Society  from  E.  H.  Uhde,  Esq.,  from  Michu- 
acca  and  valley  of  Tolucco.  It  has  the  same  tendency  as 
that  in  the  Chelsea  Gardens  to  throw  out  lateral  shoots 
from  the  collar,  but  it  is  not  now  above  three  feet  high. 
The  tubers  from  whence  it  was  raised  were  about  the  size 
of  a  small  walnut.  They  were  planted  in  July,  and  were 
in  flower  in  the  middle  of  October ;  but  up  to  that  time  no 
tubers  were  formed. 

(51.)  All  our  garden  varieties  which  exist  at  the  present 
time  have  probably  sprung  from  Gerard's  specimen  (plate 
i.),  or  some  of  the  same  period  ;  but  it  is  very  uncertain 
how  the  plant  got  to  Virginia. 

(52.)  Miller  gives  forty-four  species  of  potatoes.  A  po- 
tatoe  grower  enumerates  one  hundred  and  fifty-eight  kinds, 
with  their  respective  flavor,  height  of  the  stem,  &c.  At 
the  Horticultural  Gardens,  Mr.  Thompson  informs  me  that 
they  cultivate  two  hundred  kinds,  though  perhaps  not  more 
than  twenty  varieties  are  commonly  sent  to  the  London 
market. 

(53.)  The  peculiar  kind  of  potatoe  is  maintained  by  an 
extension  of  the  same  individual  from  a  bud.  This  bud 
may  be  either  the  whole  tuber  with  its  eyes,  the  eye  of 


OF    THE    POTATOE    PLANT.  15 

the  potatoe  alone  with  a  small  piece  of  tuber  attached,  a 
shoot  from  that  eye,  or  a  bud  from  the  haulm,  which  will 
grow  either  by  layering  or  from  a  cutting. 

(54.)  In  the  cultivation  of  the  potatoe,  man  has  espe- 
cially in  view  the  selection  of  those  varieties  the  tubers  of 
which  are  most  developed.  The  tuber  is  the  part  employed 
for  the  purposes  of  man,  and  therefore  he  selects  those  va- 
rieties which  will  give  the  largest  produce,  and  which  are 
richest  in  starch. 

(55.)  These  individual  peculiarities  which  attach  to  the 
kinds  or  varieties  of  potatoes,  are  to  the  plant  what  idio- 
syncrasy is  to  the  human  being.  Every  man  has  certain 
constitutional  peculiarities :  some  persons  even  die  from 
the  bleeding  following  trifling  operations,  others  are  poi- 
soned by  minute  doses  of  mercury ;  some  are  short,  others 
are  tall,  and  in  fact  every  one  has  something  sufficient  to 
distinguish  him  from  his  neighbors. 

(56.)  Every  kind  of  plant  evinces  these  peculiarities 
where  every  seedling  is  an  individual.  If  we  walk  along 
a  country  road  in  spring,  we  find  every  thorn  putting  forth 
its  buds  at  a  different  time ;  and  the  varieties  are  so  marked 
in  the  horse-chestnut  tree,  that  some  individual  plant  will 
be  many  days  in  leaf  before  its  neighbor  has  expanded  its 
buds. 

(57.)  Our  present  potatoe  must  not  be  confounded  with 
the  potatoe  in  use  before  1600.  The  potatoe  then  spoken 
of  is  the  Convolvulus  batata,  or  sweet  potatoe,  a  convolvu- 
laceous  plant  now  in  use  in  the  West  Indies. 

(58.)  It  is  this  potatoe  to  which  allusion  is  made  in 
Shakspeare  ("  Let  the  sky  rain  potatoes  ")  in  the  "  Merry 
Wives  of  Windsor,"  act  v.,  Scene  5  ;  the  word  "  pota- 


16       ON   THE    INDIVIDUALITY    OF   THE    POTATOE   PLANT. 

toe "  also  occurs  in  "  Troilus  and  Cressida,"  act  v., 
Scene  2. 

(59.)  About  the  year  1600,  and  for  some  time  after,  the 
convolvulus  potatoe  is  spoken  of  as  the  common  potatoe, 
and  our  present  potatoe  is  noticed  as  the  new  potatoe  of 
Virginia.  Now  the  tables  are  completely  turned  ;  the 
sweet  potatoe  is  become  the  scarce  one,  being  worth  nine- 
pence  a  pound,  and  frequently  not  to  be  procured,  whilst 
the  other  is  in  every-day  use. 

An  attempt  is  being  made  by  Dr.  Stewart  to  naturalize 
the  sweet  potatoe  in  this  country.  He  planted  his  speci- 
mens too  late  this  year,  and  therefore  no  tubers  are  formed, 
but  it  is  not  improbable  that  the  early  kinds  may  thrive 
here.  Gerard  grew  them  in  his  garden  250  years  ago. 

(60.)  Our  potatoe  received  its  name  from  Gerard,  in 
consequence  of  its  general  resemblance  to  the  sweet  tuber. 
This  plant  is  also  well  figured  by  the  same  author. 

(61.)  In  this  chapter  I  wish  particularly  to  enforce  the 
fact  that  we  are  not  using  the  wild  plant,  but  an  abnormal 
deviation  from  it ;  in  fact,  we  are  employing  plants  pecu- 
liar from  the  exaggerated  quantity  in  which  they  produce 
tubers,  and  in  which,  notwithstanding  the  increase  of 
tuber,  the  quantity  of  leaf  is  very  materially  diminished. 


17 


CHAPTER  III. 

CHEMISTRY   AND   USES   OF    THE    POTATOE. 

Ingredients  of  potatoe  (62).— Analyses  of  potatoe  (03,  64). — Sola- 
nine  (65). — Starch  (66). — Albumen  (67). — Ultimate  analyses  of 
potatoe  (63). — Gerard's  description  of  (69).— Evelyn's  (70). — Use 
of  the  potatoe  (71,  72).— Relative  value  of  potatoe  (73).— Quantity 
required  for  food  (74). — Phosphorus  in  potatoe  (76,  77). — Aphro- 
disiac properties  (78)  —Iron  in  potatoe  (79). — Modes  of  cooking 
(81). — Use  of  potatoe  for  bread  (82). — Potatoe  in  wheaten  bread 
(83).— Potatoe  a  medicine  (84).— Extraction  of  starch  (85—87). 
—Uses  of  starch  (88 — 90).— Conversion  of  starch  into  dextrine 
(91);  into  sugar  (92). — Potatoes  used  for  the  manufacture  of 
spirit  (93,  94). — Frosted  potatoes  used  for  spirit  (95) ;  for  wine 
(96). — Potatoes  for  feeding  cattle  (97)  ;  sheep  and  swine  (98).— 
Potatoe  apples  for  salad  (99).— Preserved  potatoes  (100).— Resume 
(101). 

(62.)  THE  potatoe  plant  in  a  state  of  health  contains  several 
ingredients,  the  most  important  of  which  are  starch,  albu- 
men, and  solanine.  These,  however,  do  not  exist  in  a  con- 
centrated form,  but  are  united  with  a  large  quantity  of 
water. 

(63.)  I  have  extracted  from  Dr.  Ure's  "  Dictionary  of 
Chemistry"  the  following  table  of 

ANALYSES    OF    THE    PLANT. 

Fibrin.    Starch.  Veg.Album.  Gum.  Acids  and  Water.  Analyst. 

Salts. 

5-1  75*0  Einhof. 

—  730 

—  93-0       „ 

—  81*3       „ 

—  78-0 


Red  potatoes        7'0 

150 

1-4 

4-1 

Id.  germinated    6'8 

15-2 

1-3 

3-7 

Potatoe  sprouts  2  '8 

0-4 

0-4 

3-3 

Kidney  potatoe  8  '8 

9-1 

0-8 

— 

Large  red  do.      6'0 

129 

0-7 

— 

18 


CHEMISTRY   AND    USES    OF    THE    POTATOE. 


Fibrin.    Starch.  Veg.Album.  Gum.  Acids  and  Water.  Analyst. 

Salts. 
Sweet  potatoe     8'2         15'1         O'S         —         —         74-3  Einhof. 


Potatoe  of  Peru  5 '2 
"  England  6-8 

Onion  potatoe  84 
"  Voigtland  7-1 
"  cultivated"} 

in  the  envi-     >6'79 

rons  of  Paris.    ) 


15-0 

1  9 

•    1-9 

70-OLampart 

12-9 

1-1 

1-7 

77-5       „ 

18-7 

09 

1-7 

70-3       „ 

15-4 

12 

2-0 

74-3       „ 

133         0.92 


3-3     1-4     73-12  Henry. 


(64.)  Pereira,  in  his  valuable  work  on  "  Food  and  Diet," 
gives  a  full  analysis  of  the  potatoe  by  Michalles. 


PROXIMATE    COMPOSITION    OF    THE    POTATOE. 

Water             .           '.            .          '%          '.            .  .     66875 

Starch  and  amiglaceous  fibre     .             .            .            .  30'469 

Albumen        .          ;.  ^        .        '"'.*"          .        :-  Y";  •'-.'•   0'503 

Gluten               •  „             .            i  .          .             .             .  0-055 

Fat     .          .  ,  ,, 0-056 

Gum                   %         "  '^           .            .             •             •  0-020 

Asparagin     '.           '.  "        .            .            .            .  .!     0'063 

Extractive           ......  0'921 

Chloride  of  Potassium  .....       0'176 

Silicate,  phosphate,  and  citrate  of  iron,  manganese,  ^ 

alumina,  soda,  potash,  and  lime  (of  these  potash  V  0*815 
and  citric  acid  are  the  prevailing  ingredients)         ) 

Free  citric  acid         »            .    ;        .            .            .  -t      0'047 

100  000 

(65.)  The  solanine  exists  principally  in  the  leaves  and 
stem,  and  perhaps  in  the  root  to  a  very  small  extent.  It  is 
composed,  according  to  Blanchet,  of 


Carbon. 
62-11 


Hydrogen. 
8-92 


Nitrogen. 
1-64 


Oxygen. 
27  '33 


CHEMISTRY    AND    USES    OF   THE    POTATOE.  19 

(66.)  Starch  exists  in  the  plant  in  the  form  of  rounded, 
elliptical,  or  polyhaedral  granules,  each  of  which  has  a  lit- 
tle spot  called  the  hylum,  by  which  it  is  supposed  to  be 
attached  to  the  cell  of  the  plant.  (Plate  v.,  fig.  5,  Plate 
vii.,  fig.  8.)  The  starch  granules  consist  of  concentric 
rings  or  rugae,  similar  to  those  which  starch  cells  present 
on  their  surface.  Potatoe  starch  consists  of  carbon  44'25, 
water  55-75.  The  quantity  of  starch  differs  in  different 
months,  and  the  size  of  the  granules  varies  from  the  40^0 
to  the  3J,0  of  an  inch. 


Ibs. 

In  August,  about    .         .         10 
In  September     .         .         .     14j 
In  October      .         .         .         14| 
In  November  .        .17 


Ibs. 

In  March  .         .         .        .17 
In  April  13f 

In  May      .         .         .         .10 


(67.)  I  am  not  aware  that  any  good  analysis  of  potatoe 
albumen  has  been  published ;  but  from  analogy  we  may 
suppose  that  it  consists  of  carbon,  hydrogen,  nitrogen,  and 
oxygen.  It  exists  in  the  potatoe  plant  in  a  state  of  solu- 
tion, and  separates  spontaneously  by  coagulation  from  the 
expressed  juice. 

(68.)  Regarding  the  potatoe  in  a  more  chemical  manner, 
we  find  that,  according  to  Boussingault  and  Bsechmann,  it 
is  composed  of  the  following  ultimate  elements : — 

Boussingault.  Bicchmann. 

Carbon  .  .       44-1  .  .       43  944 

Hydrogen  .  5'8       .  .  6 -222 

Nitrogen — Oxygen    .      45*1  .  .      44919 

Ashes       .  5*0  4-915 

100-0  lOO'OOO 

(69.)  Gerard  says  "  that  the  temperature  and  vertues 
be  referred  unto  the  common  potatoe  (meaning  thereby 


*0  CHEMISTRY   AND    USES    OF   THE    POTATOE.    • 

the  sweet  potatoe,  the  only  root  known  before  this  period)* 
being  likewise  a  food  as  also  a  meat  for  pleasure,  equal  in 
goodness  and  wholesomeness  unto  the  same  being  either 
roasted  in  the  embers  or  boyled  and  eaten  with  oyle,  vine- 
gar, and  pepper,  and  dressed  in  any  other  ways  by  the 
hand  of  one  cunning  in  cookeries;"  so  that  at  first  it  was 
used  as  a  luxury,  and  not  as  an  article  of  food. 

(70.)  Evelyn  states,  "  the  root  being  roasted  under  the 
embers  or  otherwise  roasted,  with  a  knife  the  pulp  is  but- 
tered, in  the  skin  of  which  it  will  take  up  a  good  quantity, 
and  is  seasoned  with  a  little  salt  and  pepper.  It  is  also 
stewed  and  cooked  in  pyes." 

(71.)  The  potatoe  is  valuable  to  man  as  an  article  of 
food,  from  the  starch  and  albumen  which  it  contains,  as 
these  two  principles  can  effectually  nourish  the  human  be- 
ing. The  one  acts  by  combining  with  oxygen  in  his  lungs 
to  give  him  warmth ;  the  other  nourishes  his  muscular 
system  and  fits  him  for  labor. 

(72.)  Neither  principle  alone  would  suffice,  for  man 
would  starve  upon  either  one ;  it  is  the  combination  then 
which  is  valuable,  and  we  find  that  this  combination  cannot 
be  produced  at  so  cheap  a  rate  from  any  other  source. 

(73.)  The  nitrogenized  portion  is  the  most  costly  to  buy, 
and  we  find  that  the  relative  value  of  the  potatoe,  in  point 
of  weight  with  other  substances,  is  as  follows  : — 

Maize,  or  Indian  corn         .     138 


Wheat  flour         .'        .    *  .  100 

Barley    .         .         .  •      .  130 

Oats           U-      .        .    -  .  117 

Rye        ....  Ill 

Rice             .         .        .  .177 

Buck  wheat   ...  108 


Peas        ....  67 

Potatoes     .         .         .  .613 

„       dried  at  212C     .  126 

Jerusalem  artichokes  .     539 

Turnips          .         .         .  1338 


These  are  termed  nutritive  equivalents,   613  parts  of 
potatoe  being  equal  to  100  wheat  flour,  &c. 


CHEMISTRY   AND    USES    OF   THE    POTATOE. 


21 


Taking  female  milk  as  the  standard,  and  making  it 
100,  MM.  Schlossberger  and  Kempt  have  given  the  follow- 
ing scale  of  the  nitrogen  contained  in  different  varieties  of 
food,  which  will  show  the  relative  value  of  the  potatoe  for 
this  purpose  : 


Female  milk 


100 


Rice       ...;v,  « 
Potatoes     . 
Turnips 
Rye 

Maize     . 
Oats 

Barley    . 
Wheat 
Wheat  bread  . 


VEGETABLE    FOOD. 


...    .       81 

.       84 

106 

.     106 

100—125 

.     138 

125 

119_144 

142 


Black  bread    . 

Bread  from  Glasgow  . 

Beans     .... 

Peas  . 

Pulse      .... 

French  beans    .       .&)?•    , 

Three  species  of  agaricus 
respectively 


166 
134 
320 
233 
276 
283 
289 
264 


ANIMAL     SUBSTANCES. 


Cow's  milk     . 

237 

Veal       . 

Cheese 

231—447 

Veal  boiled 

Yolk  of  egg    .        . 

7  *s  -.<•'     305 

Beef       . 

Oysters      .         .       -  « 

.     305 

Beef  boiled 

Eels     --l-.-^*   -^>' 

1  .'"•    434 

Pure  protein  . 

Salmon      .    j^.Jri^a 

.     776 

Pure  albumen 

White  of  egg 

843 

Pure  fibrin 

Flesh  of  pigeon  . 
Flesh  of  lamb       •>.  . 

.     756 
833 

Pure  casein 
Pure  gelatin  . 

Flesh  of  sheep  . 

.     773 

Pure  chondrin 

Flesh  of  sheep  boiled 

952 

873 
911 

880 

942 

1006 

996 

999 

]003 

1028 

910 


(74.)  From  certain  experiments  made  at  Glasgow,  it 
was  found  that  six  pounds  of  potatoes  alone  were  amply 
sufficient  for  the  food  of  a  man  per  diem ;  now  this  costs 
IJd.,  which  is  probably  the  least  possible  cost  at  which  a 
man  could  be  fed  in  ordinary  times.  An  Irishman  in 
health  and  activity  is  said  to  eat  from  ten  to  twelve  pounds 
of  potatoes  per  diem. 

(75.)  I  have  been  for  some  months  past  trying  experi- 


22       CHEMISTRY  AND  USES  OF  THE  POTATOE. 

merits  with  fowls  upon  the  value  of  various  foods  for  nutri- 
tion, but  in  the  instance  of  the  potatoe  could  obtain  no 
result.  The  fowls  ate  the  boiled  potatoes  ravenously  for  a 
few  days,  and  then  absolutely  refused  them.  10  Ib.  of 
potatoes  appeared  to  go  as  far  as  one  quart  of  wheat. 

(76.)  Potatoes  also  contain  a  large  quantity  of  phosphorus, 
which  is  supposed  to  act  as  a  stimulus  to  the  nervous  sys- 
tem. The  following  table  from  Pereira  shows  the  relative 
quantities  contained  by  the  potatoe  and  some  other  sub- 
stances : — 

Potatoe  ....  2'5 

Wheat  ....  0-792  to  1'98 

Barley  ....  022  to  1'32 

Oats  ....  0-352  to  1-32 

Rice  ....  0-286  to  0'88 

(77.)  Burnet  mentions  that  the  potatoe  is  remarkable  for 
becoming  phosphorescent  during  putrefaction,  affording 
even  light  sufficient  to  read  by.  An  instance  in  point  is 
mentioned  in  the  "  Edinburgh  Philosophical  Journal,"  in 
which  it  is  related,  that  an  officer  on  guard  at  Strasburg 
thought  the  barracks  were  on  fire,  so  great  was  the  light 
emitted  from  a  cellar  filled  with  potatoes  which  were  in  an 
incipient  state  of  decomposition. 

(78.)  It  appears  that  Clusius  had  the  potatoe  from  the 
Pope's  garden,  the  Pope  having  received  it  from  South 
America.  In  those  times  it  had  a  great  reputation  for  its 
aphrodisiac  properties,  and  therefore  it  is  especially  to  be 
avoided  by  monks,  nuns,  popish  priests,  and  others  who 
think  fit  to  make  vows  of  celibacy. 

(79.)  Iron  also  is  contained  in  the  potatoe,  and  adds 
materially  to  its  value  as  an  article  of  food,  that  metal 
being  always  required  as  a  constituent  of  the  blood. 


CHEMISTRY  AND  USES  OF  THE  POTATOE.       23 

(80.)  We  thus  perceive  that  as  an  article  of  diet  the 
potatoe  is  invaluable,  as  it  contains  hydrogen,  carbon, 
nitrogen,  phosphorus,  sulphur,  iron,  and  lime ;  all  elements 
required  for  nutrition. 

(81.)  Potatoes  can  be  cooked  either  by  boiling,  steam- 
ing, baking,  or  frying,  the  only  point  requiring  atten- 
tion being  the  application  of  the  heat,  which  should  be 
managed  in  such  a  manner  that  all  parts  may  be  cooked 
equally,  and  not  one  part  overdone  before  the  other  is 
warm. 

(82.)  Potatoes  may  be  made  into  bread  according  to 
Parmentier. '  He  first  boils  them  and  reduces  them  to  a 
very  fine  tough  paste  by  a  rolling-pin,  and  then  mixes  with 
this  an  equal  weight  of  potatoe  starch.  He  states  that 
this  mixture  makes  a  very  white,  well  raised,  pleasant 
bread. 

(83.)  Wheaten  bread  in  London  generally  contains 
potatoes,  and  I  am  informed  that  they  are  used  in  the  fol- 
lowing manner : — The  potatoes  are  generally  placed  in 
cold  water  and  boiled  for  one  hour ;  they  are  then  taken 
out  and  well  mashed ;  a  quantity  of  warm  water  is  then 
added  with  the  yeast,  and  this  is  allowed  to  stand  four  or 
five  hours.  The  mixture  is  then  strained  through  a  fine 
sieve,  and  half  the  flour  is  added,  and  worked  up  to  form  a 
sponge.  This  sponge  is  allowed  to  stand  about  six  hours, 
after  which  it  is  made  into  bread.  Donovan  states  that  4 
cwt.  of  flour  will  bear  5  stone  of  potatoes.  Potatoes  are 
also  used  for  boiled  and  baked  puddings,  cakes,  &c. 

(84.)  Not  only  for  food,  but  also  as  a  medicine,  is  the 
potatoe  valuable.  It  is  found  of  great  efficacy  when  used 
for  scurvy ;  and  Dr.  Baillie  has  lately  discovered,  at  the 
Penitentiary,  that  its  efficacy  is  not  impaired  by  boiling. 


24  CHEMISTRY    AND    USES    OF    THE    POTATOE. 

(85.)  The  starch  of  the  potatoe  is  used  in  the  arts  for 
various  purposes.  "  To  extract  it  the  potatoe  should  be 
grated  fine  (a  piece  of  iron  pierced  with  holes  makes  a 
good  grater),  and  on  a  first  attempt  I  found  that  10  Ib. 
weight  will  be  grated  by  a  boy  in  twenty-five  minutes. 
A  crushing  machine  would  be  preferable  where  large 
quantities  have  to  be  treated.  The  pulp  should  be 
thoroughly  washed  in  water,  and  the  whole  strained 
through  a  very  fine  sieve  several  times,  when  the  starch 
and  soluble  matters  will  pass  through  ;  and  after  standing 
a  short  time,  the  starch,  by  its  superior  weight,  falls  to  the 
bottom.  The  separated  liquor  should  be  poured  off,  and  the 
starch  mixed  successively  with  several  quantities  of  water 
till  the  water  becomes  quite  tasteless.  The  starch  should 
then  be  dried  in  a  warm  room,  and  thus  prepared  will  keep 
for  a  long  period." 

(86.)  Various  machines  have  been  contrived  for  per- 
forming the  operation  of  rasping  potatoes  with  rapidity,  one 
of  which,  invented  by  St.  Etienne,  is  said  to  be  capable  of 
preparing  eighteen  cwt.  per  hour. 

(87.)  The  starch  is  much  used  in  the  preparation  of 
calicoes,  but  every  judicious  housewife  will  buy  that 
unstarched.  To  detect  starch  in  calico,  apply  a  drop  of 
solution  of  iodine  in  iodide  of  potassium ;  this  shows  the 
presence  of  starch  by  striking  a  deep  blue  color. 

(88.)  Potatoe  starch  is  often  sold  under  the  name  of 
English  arrow-root,  and  is  probably  often  sold  for  the  true 
arrow-root,  being  applicable  to  the  same  purposes.  Accord- 
ing to  Christison  it  is  more  apt  to  cause  acidity.  It  is  used 
by  the  cook  in  the  preparation  of  souffles,  and  sometimes  as 
a  substitute  for  wheat  flour  in  thickening  sauces,  &c.,  on 
account  of  its  being  both  cheap  and  tasteless. 


CHEMISTRY   AND    USES    OF    THE    POTATOE.  25 

(89.)  The  refuse  of  potatoe  from  starch  making  is  em- 
ployed, according  to  Loudon,  for  cleansing  woollen  clothes 
without  injuring  their  color;  and  the  liquor  decanted  from 
the  starch  is  excellent  for  cleaning  silk  without  doing  the 
smallest  injury  to  the  color. 

(90.)  Potatoe  starch  may  be  converted  into  dextrine,  or 
British  gum,  by  merely  heating  ft.  This  substance  is  now 
largely  used  as  a  substitute  for  gum-arabic,  and  a  familiar 
example  of  this  is  furnished  by  the  postage-stamps,  which 
are  said  to  be  gummed  with  potatoe  dextrine.  Dextrine  is 
composed,  according  to  Marcet,  of  carbon  35-7,  hydrogen 
6-2,  oxygen  58-1. 

(91.)  Potatoe  starch  is  converted  into  sugar  by  means 
of  acid.  To  effect  this,  a  pound  of  starch  may  be  digested 
in  six  or  eight  parts  of  distilled  water,  rendered  slightly 
acid  by  two  or  three  drachms  of  sulphuric  acid.  The 
mixture  should  be  simmered  for  a  few  days,  fresh  portions 
of  water  being  occasionally  added  to  compensate  for  the 
loss  by  evaporation.  After  this  process  the  acid  is  to  be 
saturated  with  a  proper  proportion  of  chalk,  and  the  mixture 
filtered  and  evaporated  to  the  consistence  of  syrup  :  its  taste 
is  sweet,  and  by  purification  in  the  usual  way  it  affords 
granular  sugar. 

(92.)  This  sugar  is  manufactured  at  Bow,  but  it  con- 
tains sulphate  of  lime,  which  gives  it  an  offensive  bitter 
taste.  It  is  employed  to  adulterate  the  sugars  sold  by 
grocers  at  a  very  cheap  rate. 

(93.)  Potatoes  may  be  employed  for  the  preparation  of 
alcohol,  and  Donovan  states  that  there  are  large  manu- 
factures for  that  purpose  in  France ;  and  Cadet  states  that 
100  Ibs.  of  potatoes  will  afford  30  Ibs.  of  spirit.  The 
alcohol  may  be  obtained  either  by  fermenting  the  potatoes 

2 


26  CHEMISTRY    AND    USES    OF    THE    POTATOE. 

without  any  previous  preparation,  or  from  sugar  previ- 
ously made  from  starch. 

(94.)  The  process  is  not  followed  by  any  distiller  at 
present  in  the  United  Kingdom,  for  several  reasons  ;  first, 
because  it  would  cause  an  outlay  of  several  thousand 
pounds  for  extra  utensils  and  machinery  to  carry  on  the 
process ;  secondly,  because  the  spirit  produced  from  pota- 
toes is  not  so  good  as  that  produced  from  corn  ;  and,  lastly, 
because  our  revenue  laws  compel  us  to  produce  as  much 
spirit  from  wash  made  from  potatoes  as  from  wash  made 
from  sugar,  or  25  per  cent,  more  than  from  wash  made  from 
corn.  Thus,  100  gallons  of  wash  at  50°  of  gravity  is 
charged  from  attenuation  at  the  rate  often  gallons  of  spirit 
to  be  produced ;  and  for  any  quantity  above  that  made 
or  produced  the  duty  is  charged  on  the  additional  quantity 
of  spirit;  but  from  100  gallons  of  wash  at  50°  of  gravity, 
made  from  any  other  material  than  corn,  twelve  and  a  half 
gallons  of  spirit  are  charged,  whether  that  quantity  be  pro- 
duced or  not.  Thus,  if  we  were  working  from  potatoes  on 
an  extensive  scale,  we  might  have  to  pay  thousands  of 
pounds  of  duty  annually  for  spirit  which  we  could  not  pro- 
duce. There  was  a  potatoe  distillery  erected  near  Vaux- 
hall  turnpike  about  fifteen  or  twenty  years  ago  by  a  com- 
pany of  Frenchmen ;  but  they  only  worked  about  two 
months,  when  they  became  insolvent,  in  consequence  of 
being  charged  by  the  excise  with  much  more  spirits  than 
they  could  possibly  make  from  potatoe  wash. 

(95.)  Even  frosted  potatoes  may  be  employed  for  the 
production  of  ardent  spirits ;  and  it  is  said  that  three  bush- 
els and  a  half  of  potatoes  afford  the  same  quantity  of  spirit 
as  one  of  malt. 

(96.)  It  is  said  that  good  wine  may  be  made  from  frosted 


PL  7. 


r   -. 


- 


-. 


*      J 

••* 


CHEMISTRY    AND    USES    OF   THE    POTATOE.  27 

potatoes,  but  I  should  think  that  the  drinkers  could  be  no 
great  epicures.  The  action  of  frost,  no  doubt,  generates 
sugar  in  the  decaying  tuber. 

(07.)  Potatoes,  especially  the  coarser  kinds,  are  em- 
ployed for  feeding  cattle.  Milch  cows,  however,  when 
thus  fed,  are  supposed  to  give  large  quantities  of  milk,  but 
of  an  inferior  quality. 

(98.)  They  are  also  employed  raw  for  feeding  sheep ; 
for  swine,  however,  they  are  more  generally  steamed  or 
boiled.  In  some  places  poultry  are  fed  with  them,  and 
very  commonly  with  the  addition  of  butter-milk. 

(99.)  A  very  curious  use  of  the  potatoe  plant  is  given 
by  John  Evelyn,  which  now  doubtless  has  become  obso- 
lete. "  The  small  green  fruit,  when  about  the  size  of  the 
wild  cherry,  being  pickled,  is  an  agreeable  sallet." 

(100.)  The  Mexicans,  like  the  Peruvians,  can  preserve 
potatoes  for  whole  years  by  exposing  them  to  the  frost 
and  drying  them  in  the  sun.  The  root,  when  hardened 
and  deprived  of  water,  is  called  chama. 

(101.)  Such  are  the  various  purposes  for  which  the 
potatoe  is  employed,  and  so  valuable  to  man  are  its  uses, 
that  the  plant  has  had  an  extraordinarily  extensive  range 
of  cultivation.  Humboldt  states  that  it  is  found  from  the 
southern  extremity  of  Africa  to  Labrador,  Iceland,  and 
Lapland. 


28  PRESENT    DISEASE    IN    THE    POTATOE. 


CHAPTER  IV. 

ON   THE   GANGRENE    OF   THE   POTATOE,    OR   PRESENT    DISEASE 
IN    THE    PLANT. 

Disease  of  potatoe  (102). — Mortification  (103).—  Commencement  of 
and  propagation  in  leaves,  stalks  (104 — 107)  ;  in  under-ground 
stem  (108);  in  collar  (109).— Modes  of  proceeding  (110—113); 
in  tubers  (114)  ;  in  seeds  (120).— Odor  in  (121).— Dryness  of  leaf 
in  (122). — Diseased  plants  (123). — Plants  not  injured  (124); 
afterwards  die  (125). — Primary  effect  (126). — Entire  plant  dis- 
eased (128).— Top  of  haulm  left  (129— 132).— Continuity  of  dis- 
ease in  future  plants  (132). — Period  of  growth  when  affected  by 
disease  (134—136). — Diseased  potatoes  bad  (136).— Structure 
impaired  (137).— Decomposed  (138 — 141).— Irregular  cavity  (142, 
143). — Shrivelling  of  (143.) — General  character  of  alteration 
(144). 

(10*2.)  THE  potatoe  plant  has  lately  become  the  subject 
of  a  peculiar  disease,  by  the  operation  of  which  a  larger 
or  smaller  part  of  the  plant  loses  its  proper  characters  and 
dies. 

(103.)  This  disease  is  mortification,  or  gangrene,  in  the 
truest  sense  of  the  term,  and  presents  itself  for  our  consider- 
ation under  two  varieties,  as  gangrena  sicca,  or  dry  gan- 
grene, where  the  part  shrivels  up  and  becomes  quite  hard 
and  desiccated,  and  gangrena  liumida,  or  moist  gangrene, 
by  which  the  potatoe  becomes  disorganized  by  rotting,  and 
is  wet  and  offensive. 

(104.)  Upon  examination  we  find  that  this  gangrene 
may  commence  in  various  parts  of  the  plant,  and  produces 
consequences  important  to  the  vitality  of  the  plant,  com- 
mencing at  the  spot  which  it  first  attacks.  It  may  attack 


PRESENT    DISEASE    IN    THE    POTATOE.  29 

a  part  of  a  single  leaflet,  which  may  dry  and  become 
dead.  It  may  even  commence  at  any  portion  of  the  leaflet 
— in  the  centre  forming  a  little  dry  circle,  which  may  be- 
come a  simple  hole  ;  or  it  may  commence  on  one  side,  or 
round  the  edge  of  the  leaflet.  (Plate  v.,  fig.  4.) 

(105.)  In  some  cases  the  gangrene  is  propagated  down 
the  leaf- stalk,  thus  cutting  off  nourishment  from  the  other 
leaflets,  which  then  die  from  secondary  causes,  being  thus 
as  completely  isolated  as  if  they  had  been  removed  from 
the  plant  by  the  gardener's  knife. 

(106.)  From  the  leaf  it  may  be  propagated  down  the 
stalk,  and  in  this  way  cut  off  the  supply  from  other  entire 
leaves,  or  even  from  whole  stems,  which,  from  their  hav- 
ing no  nourishment,  must  perish. 

(107.)  At  other  times  the  malady  attacks  the  base  of 
the  leaflets  in  the  first  instance,  and  thus  cuts  off*  the  leaf 
from  further  nourishment.  It  may  in  the  same  way  attack 
any  part  of  the  stalk,  and  cause  the  death  of  the  part  above 
it. 

(108.)  Very  frequently  it  is  first  found  in  the  under- 
ground stem  of  the  plant,  or  those  parts  of  the  principal 
stem  which  are  situated  below  the  earth's  surface.  In 
this  instance  the  supply  of  nourishment  is  entirely  cut  off 
from  the  upper  part  of  the  plant ;  and  the  top  will  fre- 
quently die  from  this  cause,  as  rapidly  as  if  it  had  been 
mown  down  with  a  scythe. 

(109.)  It  is  from  this  cause  that  potatoe  plants  in  a  green 
succulent  state  seem  at  certain  times  prematurely  to  wither 
up  in  a  few  hours.  The  stems,  separated  from  the  root  by 
the  action  of  the  disease,  are  sometimes  filled  with  water 
by  a  little  rain  or  heavy  dew,  which  renders  them  fresh 
and  beautiful  to  the  sight.  They  are  sometimes  exposed 


30  PRESENT   DISEASE    IN    THE    POTATOE. 

to  a  sultry  sun,  when  they  will  wither  and  die.  In  this 
case  I  have  observed  a  most  striking  difference  between 
the  plants  in  the  morning  and  evening,  and  in  two  or  three 
days  I  have  seen  the  whole  crop  die  down  and  rot  away. 

(110.)  Previously,  however,  to  the  collar  of  the  plant 
actually  exhibiting  the  gangrene,  it  swells,  and  is  much 
distended  with  water,  and  if  scratched  with  a  nail  at  this 
time  the  preternatural  wetness  is  more  apparent.  This 
fact  is  of  very  general  occurrence ;  and  it  is  not  only 
shown  in  the  potatoe,  but  in  all  other  plants  affected  by  this 
disease,  which  I  shall  hereafter  have  to  describe. 

(111.)  I  am  not  quite  certain  whether  the  over-distended 
cells  burst,  or  whether  they  die  in  consequence  of  the  ex- 
cess of  the  aqueous  material ;  but  I  am  confident  that  this 
distension  is  speedily  followed  by  the  destruction  of  the 
part. 

(112.)  When,  however,  the  malady  does  attack  the 
plant  in  this  vital  situation,  it  is  not  necessarily  so  destruc- 
tive, for  a  portion  only  of  the  under-ground  stem  may 
perish.'  In  this  case  the  effect  upon  the  leaves  and  above- 
ground  stems  is  more  limited,  and  the  leaves  will  partially 
die. 

We  have  thus  seen  that  the  disease  has  two  general 
modes  of  proceeding  ;  in  one  of  which  the  disease  proceeds 
from  above  downwards,  in  the  other  the  plant  is  affected 
from  below  upwards. 

(113.)  In  either  case  the  tube-bearing  stems  eventually 
take  on  the  gangrene,  and  the  tubers  become  isolated  from 
the  roots,  the  leaves,  and  other  parts  of  the  plant. 

(114.)  The  tubers  themselves  at  last  become  more  or 
less  diseased,  and  sometimes  the  disease  may  be  seen  ex- 
tending from  the  tuberose  stem  to  the  tuber.  In  some 


PRESENT    DISEASE    IN    THE    POTATOE.  31 

cases  I  have  noticed  the  disease  to  commence  in  the  new 
tuber  itself,  where  the  potatoe  has  formed  new  tubers  with- 
out roots,  stems,  or  leaves. 

(115.)  When  the  tuber  is  affected,  parts  here  and 
there  become  soft,  discolored,  and  rotten.  Under  certain 
circumstances  this  altered  material  becomes  dry,  passing 
into  a  state  of  dry  gangrene  ;  in  other  cases  it  remains 
soft,  or  in  the  state  of  moist  gangrene. 

(116.)  The  disease  does  not  always  commence  at  the 
external  surface  of  the  tuber,  for  it  is  frequently  seen  a  short 
distance  inwards,  forming  an  irregular  circle  of  disease. 
This  fact  was  so  well  known,  that  I  observed  that  pota- 
toe salesmen  in  the  low  districts  were  accustomed  last 
winter  to  exhibit  a  cut  potatoe,  to  show  to  the  buyer  its 
general  condition. 

(117.)  The  part  decidedly  most  liable  to  disease  is  that 
which  lies  between  the  bark  and  an  irregular  circle,  which 
a  section  of  a  potatoe  always  presents.  This  circle  is 
formed  by  a  layer  of  spiral  vessels,  which  contain  air 
having  seven  or  eight  per  cent,  more  oxygen  than  atmo- 
spheric air.  (Plate  vii.,  fig.  3.) 

(118.)  At  times  the  ravages  of  the  gangrene  are  not 
confined  to  this  incipient  spot,  but  the  entire  potatoe  suffers 
and  becomes  disorganized  as  the  disease  continues  to  ad- 
vance. 

(119.)  Occasionally,  moreover,  after  the  lapse  of  a  longer 
period,  we  find  that  the  internal  portion  of  the  potatoe  has 
shrivelled  into  irregular  masses,  leaving  a  great  cavity  in 
the  centre,  having  somewhat  the  form  of  an  X.  (Plate 
vii.,  fig  4.) 

(120.)  Besides  the  general  effects  of  the  disease  which 
I  have  now  enumerated,  there  are  some  others  consequent 


32  PRESENT    DISEASE    IN    THE    TOTATOE. 

on  the  premature  decay  of  the  plant.  In  the  first  place, 
the  plant  perishes  before  the  tuber  is  properly  ripened,  and 
thus  the  tuber  will  be  injured  ;  in  the  second,  the  fruit 
may  perish  before  it  has  arrived  at  its  perfect  state,  and 
hence  the  seeds  may  be  incapable  of  renewing  the  species. 

(121.)  In  the  progress  of  the  malady  the  potatoe  plant 
is  observed  to  give  off  a  most  offensive  odor.  This  is  fre- 
quently an  early  symptom  of  the  existence  of  the  malady, 
and  it  will  continue  till  the  haulms  of  the  entire  field  be 
destroyed. 

(122.)  Before  the  stalk  perishes,  if  the  plant  be  atten- 
tively observed  at  the  dawn  of  day,  the  under  side  of  the 
leaf  will  be  found  to  be  perfectly  dry  :  this  is  an  undoubt- 
ed symptom  of  the  diminished  vitality  of  the  plant.  In 
the  healthy  vigorous  plant  the  under  surface  of  the  leaves 
will  be  covered  with  a  copious  dew,  doubtless  the  exhala- 
tion of  the  plant. 

(123.)  In  observing  a  large  field  we  find  that  it  is  not 
every  plant  which  perishes ;  but  that  one  here  and  there 
is  damaged,  but  not  destroyed,  and  that  this  plant  conti- 
nues its  vigorous  growth  for  some  time'  longer. 

(124.)  Upon  examining  these  vigorous  plants  they  will 
generally  be  found  to  possess  two  sets  of  under-ground  stems. 
Above  the  lower  set  the  stalk  may  be  found  to  be  dead,  and  a 
separation  to  be  thus  effected  between  them  and  the  leaf; 
but  above  the  upper  and  younger  set,  which  have  grown 
at  a  later  period,  after  the  plant  has  been  earthed  up,  the 
stalk  may  still  be  sound,  and  thus  a  continuity  preserved 
between  the  leaf  and  the  root. 

(125.)  It  does  not,  however,  preserve  its  integrity  long  ; 
the  stem,  hitherto  apparently  sound,  generally  becomes 
affected,  the  leaves  become  dry,  and  the  whole  plant  dies. 


PRESENT    DISEASE    IN    THE    POTATOE.  33 

In  this  case  the  destruction  of  the  plant  is  not  referable  to 
a  new  infection,  but  to  the  previous  existence  of  disease  in 
the  plant ;  and  thus  we  find  that  a  diseased  portion  of  a 
plant  is  very  apt  to  cause  the  disease  in  all  future  growths 
emanating  therefrom. 

(126.)  On  account  of  this  continuous  propagation  of  the 
disorder,  it  requires  much  care  at  the  present  time  to  de- 
termine the  spot  at  which  the  first  action  of  the  disease 
takes  place ;  or,  in  other  words,  to  ascertain  whether  the 
plant  be  primarily  affected  at  the  leaves  or  at  the  tuberose 
stems.  From  the  results  of  all  my  experience,  I  believe 
that  the  primary  effect  is  more  generally  first  noticed  at  the 
upper  stem,  but  that  a  diseased  tuber  tends  greatly  to  the 
destruction  of  a  plant  by  the  changes  occurring  in  the  stem 
below  the  surface. 

(127.)  Notwithstanding  innumerable  investigations  upon 
this  point,  I  wish  to  speak  with  great  caution ;  and,  in  fact, 
it  is  but  of  little  consequence  whether  the  effect  of  the  dis- 
ease is  shown  at  the  upper  or  lower  parts  of  the  plant  in 
the  first  instance,  as  there  can  be  no  doubt  that  the  malady 
severely  injures  the  entire  plant,  in  whatever  part  it  may 
originate. 

(128.)  The  mere  local  changes  in  the  plant,  or  dead 
portions  which  we  perceive,  are  the  results  of  the  malady  : 
the  disease  itself  attacks  the  entire  plant,  and,  therefore, 
the  mere  local  changes  are  really  of  no  great  importance. 
The  disease  cannot  be  said  to  reside  in  the  blotch  in  the 
leaf,  the  dead  part  of  the  stem,  or  in  the  rotten  potatoe :  it 
is  a  far  more  recondite  affair,  having  its  residence  in  the 
vital  elements  of  the  plant ;  and,  therefore,  we  may  infer 
that  it  is  a  disease  connected  with  the  sap  and  cellular 
tissue,  and  thereby  influencing  the  vital  actions  which  oc- 

2* 


34  PRESENT   DISEASE    IN    THE    POTATOE. 

cur  between  these  necessary  constituents  of  the  organic 
body. 

(129.)  Sometimes  the  potatoe  tops  lose  their  leaves  with 
the  exception  of  a  few  at  the  extreme  top,  which  will  re- 
main and  help  to  nourish  the  plant ;  at  other  times  they 
totally  rot,  and  the  mere  remains  are  to  be  seen  in  the 
field.  In  the  first  case,  the  plant  has  been  more  mature 
when  the  disease  appeared ;  in  the  second,  the  stem  has 
been  more  succulent.  The  potatoes  or  tubers  of  a  plant 
are  not  all  necessarily  destroyed  :  some  will  be  immature 
and  will  not  keep,  others  will  be  thoroughly  rotten,  and 
some  will  be  but  slightly  injured ;  and,  as  a  general  rule, 
tubers  in  all  states  are  found  on  every  diseased  plant. 

(130.)  The  tuber  suffers  less,  or,  I  may  state  generally, 
all  the  plant  suffers  less,  the  older  it  is  before  it  manifests 
the  disease,  because  the  death  of  any  part  of  the  plant 
necessarily  cuts  off  nourishment  from  the  rest. 

(131.)  It  is  remarkable  that  even  those  tubers  of  diseased 
plants  which  appear  sound  in  the  first  instance,  are  very 
apt  to  become  diseased  upon  keeping ;  and  whole  cargoes 
of  potatoes,  which,  when  shipped,  are  to  all  appearance 
perfectly  good,  prove  only  fit  for  manure  when  they  reach 
their  destination. 

(132.)  Thus  we  may  infer  that  every  part  of  a  diseased 
plant  is  diseased.  As  a  consequence  of  the  individuality 
of  a  plant  being  preserved  and  propagated  from  parent  to 
offspring,  a  plant  originally  diseased  will  continue  its  dis- 
ease in  any  new  growth  which  originates  from  it.  And 
thus  it  is  impossible  to  tell  for  how  long  the  disease  may 
continue  to  show  itself  in  the  progeny  of  a  plant  once  in- 
fected. The  probability  is,  that  in  time,  if  the  original 


PRESENT    DISEASE    IN    THE    POTATOE.  35 

cause  should  not  continue  to  act,  the  malady  would  be 
gradually  annihilated. 

(133.)  I  have  had  abundant  opportunity,  nevertheless, 
of  observing,  on  the  other  hand,  that  potatoe  plants  which 
are  the  offspring  of  formerly  infected  tubers  manifest  the 
disease  without  the  intervention  of  the  cause  which  first 
produced  it,  and  which  I  shall  hereafter  point  out. 

(134.)  The  disease  affects  plants  at  all  periods  of  their 
age,  from  the  newest  seedling  to  the  oldest  variety.  There 
is,  however,  a  difference  in  different  kinds  in  this  respect ; 
and  in  a  field  where  many  kinds  of  potatoes  are  planted,  a 
considerable  variety  is  observable  in  the  mode  in  which  the 
plant  is  attacked. 

(135.)  It  affects  plants  also  in  all  periods  of  their  growth. 
I  have  seen  it  in  a  plant  where  tubers  have  been  formed 
without  haulm  ;  I  have  seen  it  where  the  stem  has  not 
exceeded  three  inches  in  height ;  and  I  have  seen  it  in 
more  mature  plants. 

(136.)  The  examination  of  the  diseased  tuber  presents 
very  interesting  matter.  In  the  first  place,  we  observe  the 
potatoe  in  some  instances  to  have  an  undue  hardness  to  the 
feel ;  in  this  case,  where  a  thin  section  is  examined  under 
the  microscope,  the  cells  will  show  but  a  small  quantity  of 
starch,  the  granules  will  be  but  few,  and  in  some  cases 
merely  rudimentary.  (Plate  vn.,  fig.  7.) 

(137.)  At  a  later  stage  we  may  observe  these  cells 
breaking  up  into  a  brownish  material,  and  losing  their 
perfect  cellular  character.  We  perceive,  also,  fine  lines 
crossing  the  cellular  tissue  here  and  there,  phenomena  to 
which  I  shall  hereafter  more  particularly  draw  attention. 

(138.)  When  the  decomposition  is  more  advanced,  and 
the  plant  takes  on  a  more  fluid  condition,  we  find  starch 


36  PRESENT   DISEASE    IN    THE    POTATOE. 

globules  floating  about  in  a  fluid  among  broken  down  cells 
and  spiral  vessels. 

(139.)  Such  is  the  course  which  the  disease  takes  in 
gangrena  humida  ;  but  the  appearances  in  gangrena  sicca 
are  somewhat  different.  In  this  form  of  disease,  the  pota- 
toe, when  entirely  affected,  may  retain  its  outward  form ; 
and  yet,  on  being  cut  open,  there  will  be  found  a  large 
irregular  cavity  in  its  centre,  which  cavity  often  takes  the 
form  of  an  imperfect  X.  (Plate  vii.,  fig.  4.) 

(140.)  To  form  this  cavity,  the  mass  of  the  potatoe  has 
shrivelled  up,  and  presents  either  a  white  or  brown  appear- 
ance. If  this  matter  be  examined  microscopically,  it  will 
be  found  to  consist  of  starch  globules,  with  perhaps  some 
fine  lines  which  have  replaced  the  structure  of  the  plant, 
and  the  entire  cellular  tissue  will  have  vanished.  Under 
certain  circumstances  in  this  case,  the  tuber  becomes  as 
hard  and  as  dry  as  a  bit  of  wood,  and  will  even  in  some 
cases  bear  polishing.  Sometimes  a  potatoe  is  found  to  be 
partially  affected  with  dry  gangrene,  in  which  case  it  will 
fall  in  or  contract  on  one  side,  showing  a  pit  on  its  outer 
surface. 

(141.)  A  potatoe  occasionally  shows  a  cavity  in  its  in- 
terior, which  presents  little  rounded  masses,  which,  under 
the  microscope,  show  masses  of  globules  of  starch,  with 
fungoid  growths.  (Plate  vn.,  fig.  10.) 

(142.)  When  the  disease  attacks  the  plant  and  cuts 
down  the  haulm,  the  crop  of  tubers  is  rendered  deficient 
according  to  the  period  of  growth  of  the  haulm  when  it 
dies.  This  is  consonant  with  facts  previously  known,  for 
Marshall  found  that  after  the  haulm  was  cut  he  observed 
the  same  result.  He  "  took  up  two  rows  of  equal  length, 
the  haulm  of  one  of  which  had  been  previously  cut,  that  of 


CHEMISTRY    OF    DISEASE.  37 

the  other  uncut.  The  produce  of  the  uncut  ones  was  ob- 
viously the  better.  The  number  of  tubers  is,  no  doubt,  the 
same,  but  the  quantity  is  nearly  double  :  the  tubers  of  these 
large  and  fine,  of  those  small ;  and  probably  they  have  not 
increased  in  size  since  the  haulm  was  cut,  but  they  do  not 
appear  shrivelled." 

(143.)  If  we  examine  the  diseased  potatoe,  we  find  that 
the  structure  of  the  plant  is  eventually  destroyed  ;  the  cells 
which  held  the  fluid  and  contained  the  starch  granules  no 
longer  exist ;  and,  in  more  advanced  stages  of  the  disease, 
we  observe  that  there  is  left  either  a  mere  shell  containing 
starch,  or  a  shell  containing  a  fluid  holding  starch  and 
broken-down  cells  in  suspension. 

(144.)  The  disease  manifests  itself  in  a  disorganization 
of  the  framework  of  the  plant.  The  cellular  tissue,  which 
gives  the  form  and  consistence  necessary  for  the  organiza- 
tion of  the  plant,  is  destroyed,  the  vital  actions  no  longer 
take  place,  and  the  plant  dies. 


CHAPTER  V. 


CHEMISTRY    OF    DISEASE. 

Diseased  tuber  different  in  quality  (.145).— Mode  of  analysis  (147). — 
Value  of  analyses  (148). — Analyses  (149)  —Deficiency  of  fibre 
(150).— Starch  in  excess  (151).— Albumen  destroyed  (152).— 
Solly's  analysis  (153). — Diseased  potatoes  partially  destroyed 
(154). — Sugar  in  diseased  potatoes  (157). — Butyric  acid  (158) ; 
liable  to  fermentation  (159,  160). — Difference  between  the  sound 
and  diseased  potatoes  (161). 

(145.)  THE  diseased  tuber  possesses  different  qualities 


38  CHEMISTRY    OF    DISEASE. 

from  the  sound  one,  and  although  not  absolutely  destroyed 
for  the  purposes  of  man,  it  is  frequently  very  much  im- 
paired. 

(146.)  In  examining  potatoes  chemically,  we  must  bear 
in  mind  that  different  potatoes  vary  much  in  composition, 
and  even  the  same  potatoe  at  different  periods  of  time. 

(147.)  The  rough  analysis  of  the  potatoe  is  very  easily 
performed,  when  we  desire  merely  to  know  the  relative 
constituents  most  useful  to  man.  A  given  weight  of  the 
tubers  should  be  rasped  to  a  fine  powder,  these  raspings 
should  be  placed  in  cold  water  and  thoroughly  washed,  to 
separate  the  starch  from  the  fibre  :  the  liquid  should  be 
strained  through  a  fine  sieve  several  times,  and  allowed  to 
stand  to  deposit  the  starch.  The  fibre  remaining  in  the 
sieve  should  be  placed  in  a  piece  of  linen,  and  the  water 
pressed  from  it ;  and,  upon  being  dried  in  a  water-bath,  it 
will  give  the  full  amount  of  starch.  This  may  be  placed 
in  a  crucible  over  a  clear  fire,  and  thus  the  quantity  of 
ash  may  be  learnt.  After  the  starch  has  settled,  the  water 
should  be  very  carefully  poured  off  and  evaporated  to  dry- 
ness  at  a  moderate  heat,  when  the  quantity  of  albumen, 
mucus,  &c.,  will  be  indicated.  The  starch  should  then 
have  more  water  poured  upon  it,  and  be  allowed  to  settle, 
after  which  the  water  should  be  poured  away  from  the 
sediment ;  this  process  should  be  repeated  with  fresh  por- 
tions of  water  until  the  supernatant  liquid  remains  quite 
colorless.  The  water  may  then  be  finally  poured  off,  when 
the  starch  must  be  very  carefully  dried  in  a  dry  room  be- 
fore the  fire,  and  its  weight  ascertained.  The  amount  ot 
water  would  at  last  of  all  be  inferred  from  the  loss. 

(148.)  Analyses  of  rotten  potatoes  are  really  of  very  lit- 
tle use,  because,  in  every  state  of  rottenness,  great  differ- 


CHEMISTRY    OF    DISEASE.  39 

ences  will  be  observed.  In  some  cases  of  gangrena  sicca, 
an  analysis  would  show  that  the  potatoe  was  almost  con- 
verted into  starch.  In  other  cases,  when  the  potatoe  is 
fresh  and  simply  hard,  it  would  show  a  great  deficiency 
of  starch  ;  but,  if  we  took  the  produce  of  an  acre,  I  have 
no  doubt  that  the  total  quantity  of  starch  in  the  whole  space 
would  be  found  to  be  enormously  deficient. 

(149.)  The  following  are  the  results  of  two  analyses  of 
diseased  tubers,  which  were  so  thoroughly  rotten  that  the 
mass  was  only  held  together  by  the  skin.  They  were  so 
soft  that  they  required  no  grating,  and  smashed  under 
slight  pressure. 

I.  II. 

Fibre              .             .             .            4 -4  4 '6 

"      Ash       ;  '.    '         .            7  '      2  '2 

Starch  21 '4 


L-41 

•2* 


21-6 


Albumen,  gum,  &c.  .  1  '5  ) 

Ash  -3  \ 

Water        :.;      -•  .'v        .-,;/          72'0  71'8 

100-0  100-0 

(150.)  In  this  case  the  fibre  was  not  the  cellular  tissue, 
or  fibre  of  the  potatoe  proper,  but  that  of  the  peel.  We 
thus  find  that  that  important  element  of  the  plant  was  ma- 
terially diminished.  In  this  way  the  chemical  examina- 
tion of  the  diseased  root  tallies  with  the  anatomical.  When 
the  tubers  were  only  partially  diseased,  I  found  as  much 
as  seven  per  cent,  of  fibre. 

(151.)  The  quantity  of  starch  in  relation  to  the  entire 
mass  was  above  the  average  even  of  good  potatoes,  which 
I  attribute  to  three  causes  :  first,  to  the  evaporation  which 


40  CHEMISTRY  OF   DISEASE. 

the  fluid  matter  of  the  potatoe  had  suffered  ;  secondly,  to 
the  starch  being  all  absolutely  extracted,  and  scarcely  a 
single  grain  left  with  the  amylaceous  fibre,  which  would 
never  be  the  case  with  sound  potatoes ;  and,  thirdly,  to 
minute  portions  of  fibre  passing  through  the  finest  sieve. 
In  other  analyses  of  partially  diseased  potatoes  I  obtained 
23'7  per  cent,  and  23-4  per  cent,  of  solid  material  in  the 
entire  mass. 

(152.)  With  regard  to  the  albumen  and  gluten,  they 
are  in  a  diseased  state,  in  fact  in  a  state  of  putrefaction, 
and  consequently  unfit  for  all  human  purposes.  It  is 
Liebig's  opinion  that  the  vegetable  albumen  is  converted 
into  vegetable  caseine,  which  is  more  prone  to  decomposi- 
tion. 

(153.)  Solly  gives  the  following  comparison  between 
the  analysis  of  the  bread-fruit  potatoe  for  1845  and  other 
years : — 

1842.  1843.  1845. 

Starch 1074  1383  1004 

Fibre     .         .         .         .         . '             652  685  482 

Gum  and  Resin         ...          504  284  266 

Soluble  azotised  matter — Albumen      87  80  S6 

Insoluble  azotised  matter— Gluten     103  121  100 

Water       .   ,.    .    ,.,!.   .,,,.    ..         7610  7447  8063 

10000       10000       10000 

(154.)  An  interesting  fact  appears  in  my  two  analyses 
quoted  above,  which,  though  not  connected  with  the  disease, 
I  think  it  worth  while  to  mention.  It  is  there  evident  that 
the  earthy  material  exists  in  combination  with  the  three 
great  component  parts  of  the  potatoe,  the  fibre,  the  starch, 
and  the  solution  of  gluten,  so  that  it  is  divided  between 


CHEMISTRY    OF    DISEASE.  4l 

them.     The  ash  of  fibre  and  starch  is  white,  while  that  of 
albumen  is  of  a  reddish  tint — from  the  presence  of  iron. 

(155.)  Diseased  potatoes  are  not,  then,  thoroughly  de- 
stroyed. They  may  indeed  not  contain  all  the  elements 
of  food,  and,  therefore,  are  not  fit  for  perfect  nutrition ;  yet 
the  starch  may  be  turned  to  account  for  all  the  various 
purposes  for  which  that  substance  is  employed. 

(156.)  A  great  deal  has  been  said  about  the  extraction 
of  this  principle,  viz.  starch,  and  ridicule  has  been  at- 
tempted to  be  thrown  over  the  process ;  yet,  for  the  pur- 
poses of  fattening  animals,  and  of  conversion  into  dextrine 
and  sugar,  its  separation  may  be  advantageously  per- 
formed. 

(157.)  Dr.  Ure  has  pointed  out  that  sugar  is  to  be  found 
in  the  diseased  potatoes.  This  is  an  interesting  fact,  as 
it  explains  the  reason  why  diseased  potatoes  have  so  great 
a  tendency  to  sprout.  The  sugar  may  be  determined  by 
fermentation  or  other  suitable  means. 

(158.)  Mr.  Rogers  found  butyric  acid  in  rotten  potatoes 
which  had  been  buried  for  three  years  one  or  two  feet 
deep,  but  it  does  not  appear  that  it  is  found  in  the  diseased 
substance  now  under  consideration. 

(159.)  Diseased  potatoes  are  especially  liable  to  fermen- 
tation :  two  or  three  placed  in  a  bottle,  and  tied  over  with 
a  bladder,  will  give  off  gas  to  such  an  extent  as  to  distend 
the  membrane  and  finally  burst  it. 

(160.)  So  prone  are  they  to  putrefaction,  that  I  find  that 
when  they  are  hermetically  sealed  with  balsam  of  Canada, 
still  they  evince  the  property  of  fermentation  and  evolve 
gas. 

(161.)  The  diseased  potatoe  differs  from  the  sound  pota- 
toe  in  its  various  ingredients.  The  only  material  left  in 


42  RELATION     OF    THE    DISEASE 

any  degree  of  integrity  is  the  starch,  whilst  we  find  the 
gluten  in  a  state  of  utter  decomposition,  the  amylaceous 
fibre  disorganized,  a  little  sugar  formed,  and  a  new  sub- 
stance generated,  which  I  shall  hereafter  describe. 

(162.)  Looking  at  the  malady  with  a  political  eye,  we 
have  seen  in  the  diseased  potatoes  some  useful  matter 
mixed  with  abundance  of  putrid  useless  substance. 


CHAPTER  VI. 

RELATION    OF    THE    DISEASE    TO  INTERNAL    CAUSES. 

Gangrene  from  old  age  (104). — Kinds  not  equally  affected  (165). — 
Progress  of  disease  in  Chelsea  wild  plant  (166) ;  in  Uhde's  plant 
(167) ;  in  various  varieties  (168) ;  in  plants  requiring  much  leaf 
(170). — Horticultural  Society's  plant  (172). — Greatrex's  account 
(175). — Storr's  account  (176).— Latham's  account  (177).— Early 
varieties  less  liable  to  disease  (179). 

(163.)  IT  is  difficult  to  imagine  how  any  organic  body 
should  produce  within  itself  means  for  its  own  destruction  ; 
yet  we  perceive  in  our  own  bodies  that  man  gets  old,  his 
organs  no  longer  perform  their  functions,  he  ceases  to  live, 
and  is  gathered  to  his  fathers. 

(164.)  A  theory  has  been  started,  that  the  potatoe,  being 
but  a  variety,  has  had  its  career ;  that  the  plant  has  be- 
come old,  and  is  now  dying.  Facts,  however,  do  not  bear 
out  this  assertion,  for  I  have  see  this  year's  seedlings  as 
much  diseased  as  the  oldest  variety.  The  malady  has 
paid  no  respect  to  youth  or  to  age,  but  has  cut  down  pota- 
toe plants  in  all  periods  of  their  existence. 


TO    INTERNAL    CAUSES.  43 

(165.)  Every  particular  kind  of  potatoe,  however,  is  not 
equally  prone  to  disease,  or  rather,  I  may  say,  to  carry 
its  individuality  or  peculiarity  into  its  diseased  condition. 
The  supposed  original  Chelsea  potatoe  seems  to  resist  the 
action  of  this  malady  nobly,  the  disease  only  attacking  it 
from  leaf  to  leaf,  and  not  affecting  so  materially  the  under- 
ground stems. 

(166.)  I  have  carefully  examined  this  specimen,  in  or- 
der to  observe  how  it  would  be  attacked,  and  I  found  that 
the  large  leaves  were  all  destroyed,  and  that  the  disease 
progressed  from  the  large  leaves  to  those  somewhat  small- 
er, and  so  crept  on  till  it  progressed  to  the  top.  In  conse- 
quence of  this  mode  of  attack,  the  main  shoot  and  all  the 
lateral  shoots  were  green,  healthy,  and  vigorous,  and  the 
plant  appeared  to  a  casual  observer  to  be  quite  healthy ; 
and  the  large  leaves,  or  those  out  of  sight,  being  alone  de- 
stroyed up  to  October  the  16th,  the  plant  was  still  growing 
vigorously. 

(167.)  At  the  Horticultural  Society's  Garden,  on  my 
first  visit,  Uhde's  wild  potatoes  showed  the  disease  only 
on  the  leaflet,  and  on  a  subsequent  occasion  there  was  also 
one  other  leaf  curled.  In  both  cases  I  removed  the  dis- 
eased leaf,  and  found  that  they  were  inhabited  by  a  para- 
site, which  I  shall  hereafter  describe. 

(168.)  No  two  kinds  of  potatoes  show  the  effects  of  the 
disease  equally ;  and  it  is  generally  supposed  that  that  po- 
tatoe which  ripens  in  the  early  period  of  the  year,  mani- 
fests the  malady  less  than  those  which  ripen  later,  so  that 
the  early  Shaws  are  tolerably  free  from  it. 

(169.)  On  examining  a  field  in  which  many  varieties  are 
cultivated,  every  sort  will  be  found  to  exhibit  the  malady 


44  RELATION     OF    THE    DISEASE 

in  its  own  way ;  some  varieties  will  be  more  diseased  than 
others,  and  some  will  die  down  earlier  than  others. 

(170.)  Some  potatoes  require  more  leaf  than  others,  and 
I  have  no  doubt  that  those  which  require  an  extensive  crop 
of  leaves  are  more  prone  to  be  influenced  by  the  disease 
than  others. 

(171.)  There  is  one  kind  of  potatoe  which  has  been 
lately  raised,  which  is  called  by  the  gardener  a  "  go-be- 
fore," which  arrives  at  maturity  earlier  in  the  open  bor- 
der than  any  kind  before  known,  and  which  has  a  top  only 
eight  or  nine  inches  high.  The  haulm  is  said  to  be  ripe 
by  June,  and  thus  does  not  exhibit  the  disease. 

(172.)  At  the  Horticultural  Society's  potatoe-ground, 
many  kinds  were  found  to  have  the  tubers  quite  healthy, 
while  others  were  much  diseased.  The  white-eyed  red 
was  of  the  former  class ;  the  Sourris  Jaune  of  the  latter. 
I  dare  say  that  it  will  be  found  that  the  more  nearly  the 
tuber  reverts  back  to  Gerard's  old  type,  the  more  capable 
it  will  be  of  resisting  the  disease.  The  white-eyed  red 
was  in  some  respects  similar  to  the  old  species  in  the 
Chelsea  Garden. 

(173.)  I  applied  at  the  Horticultural  Society's  Gardens 
for  a  return  of  the  relative  number  of  good  potatoes  to  bad 
ones  in  each  sort  cultivated  by  them,  but  was  unable  to 
obtain  it,  as  a  similar  return  was  ordered  to  be  printed  in 
their  own  Transactions. 

(174.)  However,  after  I  had  examined  their  potatoe* 
ground,  I  found  that  I  incurred  no  great  loss  by  being 
debarred  from  obtaining  the  above-mentioned  return,  for  I 
found  that  the  disease  had  visited  them  with  a  compara- 
tively lenient  hand  this  year,  and  that  it  did  not  exhibit 
itself  in  its  most  destructive  form. 


TO   INTERNAL    CAUSES.  45 

(175.)  Mr.  Greatrex  has  favored  me  with  the  following 
statement,  which  is  valuable,  because  the  disease  attacked 
his  neighborhood  very  severely.  "  The  crop  is  less  than 
that  of  last  year,  not  yielding  in  some  situations  more  than 
one  bushel  per  rood  (good  and  bad),  and  these  unusually 
small ;  but  it  is  believed  that  the  tubers  which  have  come 
to  maturity  keep  better  than  those  of  last  year.  In  this 
district  a  large  common  was  inclosed  three  years  back 
(light  soil).  This  land  bore  a  good  crop  last  year,  and 
has  this  year  escaped  better  than  any  other  land  in  the 
neighborhood :  it  is  situated  about  100  feet  above  a  large 
meer  of  forty-seven  acres,  which  may  perhaps  be  consi- 
dered to  have  arrested  the  blight.  Light  soils  have 
answered  best. 

"Previous  to  August  all  the  early  kinds  were  sound 
and  productive. 

"  Several  gentlemen  have  had  foreign  seed,  and  have 
not  half  the  average  crop  of  good  and  bad." 

Quantity.  Bad. 

Bread-fruit 

Farmer's  Glory        •"!'/'' 

Red  and  White  do.         gjj  c.'$\ 

Willow-leaf 

Keen's  Seedling  . 

London  Olives  . 

Irish  Tabs 

Irish  (pink) 

Sir  Watkins         .  &•**.'• 

Knapsacks 

2d  Kidneys        ;  ..  .. 

Blue  Ruffs 

Buckshin  Kidney 

Lancashire 


46      RELATION    OF  THE    DISEASE    TO    INTERNAL    CAUSES. 

Quantity.  Bad. 

Mangel  Worzel  .  2  bush. 

Early  Kidney         ,,^  t  .      good  crop 

Average  in  good  year,  4  bushels  per  rood. 

(176.)  Mr.  Storr  states  that  the  "  potatoe  crop  has 
failed  in  the  neighborhood  of  Howder,  Yorkshire,  very 
seriously.  The  Scotch  reds  are  much  the  worst.  I 
planted  twenty  tubs  of  them  last  spring,  and  have  not  more 
than  ten  tubs  fit  for  use  from  them,  and  this  is  the  case  all 
through  Marshland.  The  white  ones  are  much  better, 
say  about  thirty  tubs  per  acre  fit  for  food ;  but  they  are 
very  small,  the  haulm  having  been  prematurely  killed  by 
the  disease." 

(177.)  Mr.  Latham,  one  of  the  great  potatoe  growers  in 
Yorkshire,  says,  that  "  Many  expedients  were  resorted  to 
during  the  last  winter,  such  as  early  planting  and  deep 
planting;  and  in  some  cases  the  crop  of  1845  was  suffered 
to  remain  in  the  ground,  and  the  winter  proving  mild,  no 
serious  consequences  from  frost  took  place.  So  far  as  my 
observation  extends,  the  early  planted  potatoes  are  the  freest 
from  disease,  the  largest  in  size,  and  the  best  crop,  but  cer- 
tainly not  less  than  one-third  was  bad  even  in  these.  On 
some  of  the  best  potatoe  soils  the  crop,  in  many  instances, 
is  a  total  failure.  The  quantity  per  acre  will  vary  from  40 
bushels  to  100,  but  there  are  very  few  instances  of  the 
latter  quantity  being  obtained.  It  is  perhaps  worthy  of 
remark,  that  red  potatoes  were  those  most  severely 
affected  in  1845,  and  white  ones  in  the  present  year." 

(178.)  From  these  facts  we  discover,  that,  although  a 
potatoe  plant  might  become  old  and  might  die,  death  from 
old  age  is  not  the  cause  of  the  present  epidemic,  and  that 
old  and  young,  according  to  their  deviation  from  the  state 


RELATION    OF    THE    DISEASE    TO   EXTERNAL    CAUSES.      47 

of  nature,  become  more  or  less  affected  with  the  malady, 
and  die  either  locally  or  generally. 

(179.)  The  above  statements  also  show  that  early  kinds, 
which  are  ripe  before  August,  are  generally  less  affected 
by  the  disease. 


CHAPTER  VII. 

RELATION   OF  THE   DISEASE  TO   EXTERNAL   CAUSES,  TEMPERA- 
TURE, LIGHT,  ELECTRICITY,  ETC. 

Gangrene  not  the  result  of  any  internal  cause  (180).— Effect  of  tern-  . 
perature  upon  plants  generally  (181). — Potatoe  thrives  in  various 
climates  (182).— Cold  (184).— Influence  of  temperature  (185) ; 
upon  the  decay  of  tubers  (187).— Effect  of  light  upon  plants 
(190).— Effects  of  light  upon  tubers  (193).— Influence  of  electri- 
city (194). — Influence  of  atmospheric  moisture  on  plants  (195). — 
Excessive  moisture  a  cause  of  disease  (196) ;  its  influence  on  the 
disease  (197);  effect  on  the  tubers  (199);  other  atmospheric 
agents  (200).— Effect  of  winds  (201). 

(180.)  As  we  cannot  explain  the  gangrene  by  the  sup- 
position  of  its  origin  from  internal  causes,  and  as,  on  the 
contrary,  facts  forbid  us  to  assign  any  such  causes  for  the 
malady,  we  are  led  in  the  next  place  to  inquire  into  the 
effects  of  external  agents  upon  the  plant. 

(181.)  Every  plant' requires  a  certain  temperature,  or 
rather  a  certain  range  of  temperature,  which  is  indispensa- 
ble to  its  existence.  The  plant  of  the  frigid  region  soon 
grows  itself  to  death  in  the  torrid  region,  and  the  plants  of 
the  torrid  regions  soon  cease  to  grow  in  the  arctic. 


48     RELATION    OF    THE    DISEASE    TO    EXTERNAL   CAUSES. 

(182.)  The  potatoe  plant  has  a  wide  distribution,  and 
lives  under  varied  circumstances  better  than  most  other 
plants,  as  I  have  before  observed.  . 

(183.)  If  the  life  and  death  of  a  plant  depend  upon  the 
variations  of  temperature,  it  is  fair  to  suppose  that  lesser 
alterations  of  temperature  will  influence  the  health  of  the 
plant,  and,  in  some  cases,  tend  to  disease. 

(184.)  Cold  has  been  assumed  as  the  cause  of  the 
present  potatoe  disease  ;  but  if  we  look  to  the  average  of 
three  years,  during  which  the  disease  has  been  known  to 
be  prevalent,  we  find  that  it  cannot  be  from  that  cause.  In 
fact,  the  spring  and  summer  of  1846  have  been  remarka- 
ble for  their  extreme  heat,  so  much  so  that  the  out-door 
grapes  have  attained  extraordinary  perfection,  and  the 
larger  kinds  of  Indian  corn  have  completely  ripened  in  the 
open  air. 

(185.)  Temperature  does  not  cause  the  disease,  although 
it  has  an  important  influence  upon  it.  In  the  first  place, 
when  the  disease  cuts  off  the  supply  of  the  sap  from  the 
leaflet,  the  leaf  and  the  stalk,  or  the  entire  haulm,  it  fre- 
quently happens  that  a  very  hot  day  will  affect  a  large  plot 
of  potatoe  haulms  at  once,  and  dry  them  up. 

(186.)  I  watched  the  potatoes  the  first  thing  in  the  morn- 
ing before  I  went  \o  business,  the  moment  I  returned,  and 
the  last  thing  at  night ;  and  there  were  hot  days  when  the 
change  produced  from  this  cause  exceeded  all  belief. 

(187.)  Temperature  has  an  important  influence  upon  the 
decay  of  the  tuber ;  and  it  has  so  happened  that  in  ships' 
cargoes,  where  the  potatoes  were  sound  when  put  on  board, 
yet  when  they  were  in  the  ship's  hold  they  became  heated, 
and  not  one  sound  one  remained.  In  fact,  I  have  been 
informed  that  many  tons  were  in  such  a  bad  state  last  year 


RELATION    OF    THE    DISEASE    TO    EXTERNAL   CAUSES.      49 

when  they  arrived  at  London,  that  they  were  only  applica- 
ble for  manure. 

(188.)  To  preserve  potatoes,  especially  when  they  are 
suspected  to  have  a  predisposition  to  the  gangrene,  it  is 
almost  essential  that  they  should  be  kept  in  a  cold  place. 

(189.)  An  improper  temperature  may  then  cause  death 
in  the  potatoe,  though  it  is  not  to  be  assumed  that  it  has 
produced  the  present  malady.  Excessive  heat,  under 
certain  circumstances,  materially  influences  the  progress 
of  the  disease,  and  hastens  the  death  of  the  plant  and  its 
consequent  putrefaction. 


LIGHT. 

(190.)  Every  plant  requires  a  certain  amount  of  light ; 
many  plants  are  killed  by  a  strong  light,  and  others  will 
die  in  the  shade. 

(191.)  Absence  of  light  has  been  assumed  as  a  cause 
of  the  disease,  but  the  examination  of  the  last  three  years 
shows  that  it  cannot  be  assigned  either  to  a  deficiency  or 
superabundance  of  this  agent. 

(192.)  The  action  of  light  upon  the  tubers  is  supposed 
to  mature  them,  and  to  render  them  especially  fit  for  plant- 
ing. Potatoes  when  exposed  to  the  sun's  light  become 
green ;  in  fact,  they  become  above-ground,  instead  of 
under-ground  stems. 

(193.)  Potatoes  required  for  keeping  should  be  protected 
from  the  influence  of  light,  being  thus  less  prone  to  grow 
or  sprout,  as  it  is  termed.  In  fact,  light  favors  all  changes. 
Absence  of  light  may  cause  the  death  of  the  potatoe,  but  it 
cannot  be  said  to  have  produced  the  present  epidemic. 

3 


50     RELATION    OF    THE    DISEASE   TO    EXTERNAL    CAUSES. 
ELECTRICITY. 

(194.)  Nothing  is  known  of  the  influence  of  electricity 
upon  the  growth  of  plants.  The  world  was  startled  a  year 
or  two  ago  by  the  notion  that  electricity  was  to  serve  the 
purposes  of  manure ;  there  is  no  doubt,  however,  that  the 
author  of  this  idea  was  mistaken.  The  influence  of 
artificial  electricity  upon  plants  is  unknown  ;  and,  in  fact, 
the  artificial  application  of  electricity  has  not  been  proved 
to  exert  any  influence  whatever.  To  conduct  experiments 
on  this  subject  would  entail  much  labor  and  expense  upon 
the  experimenter,  but  I  believe  they  would  be  well  worth 
trying  in  a  manner  different  from  former  experiments. 


HYGROMETRIC    CONDITION    OF    THE    ATMOSPHERE. 

(195.)  Every  plant  requires  a  certain  hygrometric  con- 
dition of  atmosphere.  Hence  some  plants,  as  ferns,  require 
a  moist  atmosphere  ;  other  plants,  the  flowering  plants  for 
instance,  require  an  atmosphere  which  is  dryer. 

(196.)  Too  much  moisture  prevents  the  woody  fibre  from 
being  perfectly  ripened  -,  and  the  wet  season  of  last  year 
has  been  assumed  as  a  cause  of  the  potatoe  disease.  This 
year,  however,  has  been  especially  the  reverse,  and  yet 
the  disease  continues  or  even  increases. 

(197.)  Moisture  is  not  the  cause  of  the  disease,  although 
it  may  influence  it.  When  the  under-ground  stems  are 
cut  off  by  gangrene,  a  moist  atmosphere  will  fill  and  swell 
out  the  haulm  with  water,  when  a  hot  day  subsequently 
acting  upon  it  will  totally  destroy  it  and  cause  it  to  rot. 

(198.)  Potatoe  tubers  kept  in  a  wet  atmosphere  I  have 


RELATION    OF    THE    DISEASE    TO    EXTERNAL    CAUSES.      51 

found  prone  to  rot :  it  is,  therefore,  advisable  to  keep  them 
in  a  place  which  is  both  cold  and  dry. 

(199.)  Moisture,  then,  is  sufficient  to  cause  local  or 
general  death  of  the  potatoe  plant.  It  has  not,  however, 
produced  the  present  epidemic,  though  in  solitary  cases  it 
may  have  influenced  the  progress  of  the  malady. 


OTHER    QUALITIES    OF    THE    ATMOSPHERE. WINDS. 

(200.)  There  are  evidently  other  qualities  of  the  atmo- 
sphere, besides  heat,  light,  moisture,  and  electricity.  Many 
persons  can  tell  in  bed  when  the  east  wind  blows ;  and 
such  a  deleterious  influence  is  exerted  by  this  wind,  that 
every  angler  knows  that  he  fishes  in  vain  under  its  pesti- 
ferous blast. 

(201.)  The  apparent  influence  of  the  east  wind  upon 
vegetation  is  to  stunt  it,  and  to  arrest  the  progress  of  its 
growth.  In  this  way  it  may  favor  the  disease  to  a  certain 
extent :  there  is  not,  however,  the  slightest  reason  to  believe 
that  it  actually  produces  it.  The  motion  or  stagnation  of  the 
air  also  influences  vegetation  :  some  plants,  like  fungi,  like  a 
close  confined  atmosphere,  others  like  a  more  exposed  situa- 
tion. It  is  also  apparent  that  as  the  atmosphere  contains 
carbonic  acid,  the  chief  food  of  plants,  the  health  of  the 
plant  might  be  influenced  by  a  proper  proportion  of  that 
gas.  No  evidence  has,  however,  been  afforded  that  any 
variation  in  amount  has  existed  to  cause  the  present 
malady. 

(202.)  Various  hurtful  agencies  appear  to  exist  which 
are  not  referable  to  any  of  the  above  causes ;  for  instance, 
the  cholera  morbus  in  man  seems  to  arise  from  some  such 


52         RELATION    OF    DISEASE    TO    SOILS    AND    MANURES. 

unknown  agent.     The  cause  of  the  potatoe  disease  does 
not  appear  at  all  analogous  to  any  agent  of  this  kind. 

(203.)  Upon  the  whole  it  is  probable  that  certain  ab- 
normal qualities  of  the  atmosphere  have  influenced  to  a 
very  slight  extent  the  present  universal  epidemic. 


CHAPTER  VIII. 

RELATION    OF    DISEASE    TO    SOILS    AND    MANURES. 

Soil  which  suits  the  potatoe  (205). — Diseased  in  all  soils  (206). — 
Statement  of  Mr.  Latham  (207) ;  of  Mr.  Greatrex  (209).— Influ- 
ence of  wet  soils  on  the  disease  (211). — Guano  and  Animal  Salts 
(214). — Influence  of  manures  on  the  disease  (216). 

(204.)  EVERY  plant  requires  a  peculiar  soil  in  which  to 
vegetate  ;  thus,  ferns  like  a  peaty  soil,  wheat  a  rich  loamy 
soil  ;  other  plants  thrive  only  in  a  sandy  soil,  and  'in  fact 
every  plant  has  a  peculiar  soil  in  which  it  grows  best. 

(205.)  The  potatoe  plant  succeeds  best  in  a  rich  allu- 
vial soil ;  and  in  Yorkshire,  where  potatoes  are  grown  for 
the  London  market,  it  is  a  common  practice  to  allow  water 
to  deposit  a  sediment  over  land,  till  two  or  three  feet  of 
rich  mould  are  deposited. 

(206.)  It  might  be  thought  that  a  wrong  soil  has  caused 
this  epidemic,  but  the  disease  is  to  be  found  in  every  kind 
of  earth  whatever.  It  is  found  round  London  in  the  light 
alluvial  soils  left  by  the  rivers  Thames  and  Lea  ;  and  it  is 
found  in  the  stiff  London  clay,  and  in  light  gravel. 


RELATION    OF    DISEASE    TO    SOILS   AND   MANURES.        53 

(207.)  It  is  found  in  wet  soils,  and  also  in  the  dry  sandy 
soils  round  London  ;  and,  in  fact,  there  is  no  kind  of  earth 
which  will  protect  the  plant  from  the  malady.  Mr.  La- 
tham, a  large  potatoe  grower  at  Wressall  Castle,  York- 
shire, states,  in  a  letter  to  me,  "  that  fresh  land,  poor  land, 
sand  land,  clay  land,  and  good  warp  land,  are  all  equally 
susceptible  of  its  influence,  and  at  about  the  same  time." 

(208.)  Mr.  Greatrex  informs  me  "  that  all  newly  tilled 
land  has  answered  best,  and  in  some  situations  near  here 
there  may  be  two  bushels  of  potatoes  per  rood,  good  and 
bad,  which  is  less  by  more  than  one-half  than  the  average 
crop.  In  land  well  limed  and  another  well  sooted,  although 
seed  was  used  from  Bedfordshire,  where  no  disease  ap- 
peared, the  crop  was  equally  bad." 

(209.)  I  have  also  seen  the  disease  in  one  case  where 
a  potatoe  tuber  had  fallen  accidentally  under  some  old 
planks,  and  in  this  situation  was  completely  sheltered  from 
all  moisture ;  in  fact,  the  bank  was  so  dry,  that  it  was 
wonderful  how  any  plant  could  live  at  all. 

(210.)  Perhaps  the  most  curious  case  is  that  of  an  old 
potatoe  throwing  out  diseased  tubers,  when  it  had  never 
been  in  any  soil,  or  even  out  of  the  house.  In  this  in- 
stance it  was  no  doubt  the  propagation  of  the  disease  from 
a  formerly  damaged  tuber,  a  phenomenon  which  I  shall 
hereafter  more  fully  explain. 

(211.)  There  is,  then,  no  reason  for  believing  that  the 
disease  has  been  produced  by  the  influence  of  peculiar  and 
inappropriate  soils,  but,  on  the  contrary,  there  is  every 
reason  to  suppose  that  it  has  not  had  its  origin  from  this 
cause.  Although,  however,  it  has  not  been  produced  by 
soils,  it  is  nevertheless  the  concomitant  testimony  of  all  ob- 


54         RELATION    OF    DISEASE    TO    SOILS    AND    MANURES. 

servers,  that  a  heavy  Wet  clayey  soil  greatly  favors  the 
mischief. 

(212.)  It  has  been  observed  by  many  persons,  that  in 
sand  or  peat  the  disease  has  not  shown  itself  to  its  full  ex- 
tent ;  but  in  quoting  a  general  opinion,  I  have  no  precise 
facts  to  warrant  my  making  any  assertion.  Mr.  Stone 
states,  that,  "  in  his  opinion,  a  light  soil  without  manure  is 
less  subject  to  disease  than  a  better  soil  well  cultivated." 

(213.)  Some  persons  have  imagined  that  our  mode  of 
treatment  is  injurious,  and  that  the  process  of  ridging  up  is 
deleterious.  This,  however,  deserves  no  credit,  for  I  have 
seen  the  disease  in  hundreds  of  plants  which  have  never 
been  banked  up,  and  even  in  tubers  half  of  which  were 
quite  green  from  exposure  to  the  light  and  air. 

(214.)  Next  to  soils,  manures  have  attracted  attention, 
and  the  guano  from  Ichaboe  has  been  blamed.  Now,  the 
redundancy  of  animal  salts  is  calculated  to  materially  in- 
jure plants.  I  placed  some  crocuses  in  a  solution  of  that 
character,  which  grew  and  flourished,  and  became  in- 
tensely green.  Instead  of  flowering,  however,  the  roots 
began  after  a  time  to  die,  and  finally  the  entire  plants  were 
destroyed.  No  doubt,  guano  in  excess  may  act  highly  in- 
juriously, but  no  evidence  can  be  adduced  that  it  ever 
caused  the  potatoe  disease.  Mr.  Stone  states  that  he  did 
not  use  any  manure  except  on  one  piece,  where  he  applied 
some  pigeon's  dung,  and  there  he  found  most  of  the  pota- 
toes good  for  nothing. 

(215.)  I  am  informed  that  London  returns  its  manures 
to  Yorkshire,  from  whence  the  metropolis  derives  its  sup- 
plies of  potatoes  ;  and  in  various  parts  of  the  country  every 
kind  of  manure  is  used  to  further  the  growth  of  the  potatoe 
plant. 


PI.  3. 


aji.  del  Jf.Y! 


RELATION    OF   THE    DISEASE    TO    FUNGI.  55 

(216.)  Manures,  from  their  stimulating  character,  have 
doubtless  an  influence  on  the  disease  ;  and,  as  far  as  I  can 
learn,  those  plants  are  freest  from  disease  which  grow  on 
soil  which  has  been  left  quite  unmanured.  The  only 
manner,  however,  in  which  manures  do  injury,  is  by  caus- 
ing the  plant  to  assume  a  very  succulent  and  cellular 
character. 


CHAPTER  IX. 


RELATION    OF    DISEASE    TO    FUNGI. 

Berkeley's  opinion  (217). — Fungi  common  to  decaying  matter 
(219).— Fungi  on  decaying  tubers  (221).— Botrytis  infestans  (223). 
— Fungus  in  the  inside  of  tubers  (226). — Different  fungi  growing 
in  rotten  tubers  (227—230  ) — Black  fungus,  on  stem  (231). — 
Other  species  of  fungi  (232,  233)  —Singular  appearance  of  motion 
in  fungi  (234). — Fungi  influence  the  disease  (237).— Fungi  fulfil 
important  functions  in  nature  (238— 240).— Gangrena  sicca  and 
humida  (241). — Tubers  infected  with  fungi  perhaps  injurious  as 
food  (241). 

(217.)  MR.  BERKELEY  states,  that  "  to  his  own  apprehen- 
sion it  appears  clear  that  the  cause  of  the  premature  decay 
and  putrefaction  of  the  haulm  is  to  be  found  in  the  parasi- 
tic fungus,  in  consequence  of  whose  attacks  the  tubers  are 
unripe,  and  in  a  bad  state  for  preservation." 

(218.)  His  article  upon  this  subject  is  well  worth  perus- 
ing, and  the  figures  with  which  it  is  illustrated  are  ex- 


56  RELATION    OF   THE    DISEASE    TO    FUNGI. 

cellent ;  nevertheless,  his  facts  do  not  bear  him  out  in  the 
opinion  which  he  has  promulgated. 

(219.)  All  decaying  matter  .becomes  rapidly  covered 
with  fungi;  and  if  we  examine  rotten  potatoes,  we  find 
that  they  form  no  exception  to  the  rule. 

(220.)  The  question  of  the  origin  of  these  fungi  is  one 
of  great  importance  and  intricacy,  involving  as  it  does  the 
whole  question  of  equivocal  generation  :  certain  it  is,  how- 
ever, that  they  frequently  make  their  appearance  in  cases 
where,  to  our  senses,  the  possibility  of  their  existence  would 
almost  be  precluded. 

(221.)  If  we  watch  potatoes  affected  with  the  disease, 
we  shall  observe  in  some  cases  that  the  potatoe  is  attacked 
with  dissimilar  fungi.  One  of  the  most  beautiful  with 
which  I  am  acquainted  may  often  be  found  in  the  inner 
cavities  of  the  diseased  tuber ;  it  is  one  of  the  most  beauti- 
ful microscopic  objects  which  can  possibly  be  conceived. 
It  has  long  slender  threads  running  about  upon  the  surface 
of  the  decayed  matter,  and  sends  up  stems  with  a  large 
round  ball  at  the  top,  which  when  mature  becomes  covered 
with  sporules  for  its  reproduction. 

(222.)  This  beautiful  fungus  is  frequently  to  be  found  in 
the  shrivelled  cavities  of  diseased  tubers.  Sometimes  a  cut 
surface  will  be  covered  with  it,  giving  the  appearance  of  a 
most  beautiful  miniature  forest ;  and  I  am  now  writing  with 
a  specimen  before  me,  having  thousands  of  these  seed-ves- 
sels rising  upwards  in  every  stage  of  growth.  In  their 
early  stage  they  are  white,  later  they  are  brown,  and 
finally  they  are  quite  black,  and  covered  with  myriads  of 
seeds.  This  fungus  sometimes  sends  forth  these  growths 
through  the  cuticle  of  the  potatoe,  bursting  its  way  out- 
wards, and  presenting  its  numerous  heads  to  our  view. 


RELATION    OF    THE    DISEASE    TO    FUNGI.  57 

(Plate  in.,  fig  1.)     I  have  seen  the  same  or  a  very  similar 
fungus  on  glue  and  in  other  situations. 

(223.)  Another  species  is  also  said  to  be  found  on  the 
decaying  leaves,  and  likewise  on  the  tubers.  It  has  been 
called  the  Botrytis  infestans  ;  and  this  is  the  specific  fun- 
gus which  Berkeley  believes  to  cause  the  disease.  There 
cannot,  however,  be  any  question  that  the  fungus  is  a  con- 
sequence, and  not  a  cause  of  the  malady. 

(224.)  Berkeley  says  that  this  fungus*  is  to  be  found  in 
the  first  instance  in  the  cells,  before  it  bursts  through. 
The  Botrytis  is  not  always  of  the  species  described  by 
Berkeley,  for  Martius  has  figured  a  different  one,  to  which 
he  assigns  the  cause  of  the  malady,  and  has  beautifully  and 
correctly  figured  the  manner  in  which  this  kind  of  fungus 
pushes  forwards  through  the  cuticle  into  the  atmosphere. 

(225.)  I  am  very  uncertain  about  the  species  of  fungus 
figured  by  Berkeley.  I  have  figured  one  something  like 
it,  growing  on  the  edge  of  a  leaf,  and  another  variety 
which  was  growing  upon  an  under-ground  stem,  and  which 
I  take  to  be  either  the  same  or  an  allied  species.  (Plate 
in.,  fig.  6;  Plate  iv.,  fig.  6.) 

(226.)  A  fungus  is  to  be  found  frequently  in  the  interior 
of  the  tuber,  amongst  the  grains  of  starch  ;  and  in  this  case 
the  microscope  shows  nothing  but  starch  and  fungoid 
fibre.  The  mass  appears  to  the  naked  eye  like  a  piece 
of  boiled  potatoe.  This  is  probably  analogous  to  mush- 
room spawn ;  but  to  what  species  it  may  be  assigned,  I  do 
not  with  certainty  know.  (Plate  vn.,  fig.  9.) 

(227.)  A  fourth  species  presents  a  reddish  aspect,  and 
forms  one  great  mass  in  the  interior  of  the  tuber.  Ex- 
amined with  the  microscope,  the  edges  are  one  mass  of 

3* 


•    ' 
58  RELATION    OF    THE    DISEASE    TO    FUNGI. 

fine  lines,  but  the  red  part  appears  opaque.  What  it  is,  I 
do  not  know. 

(228.)  Sometimes  in  a  rotten  potatoe  we  find  that  there  is 
a  sort  of  growth  of  a  brilliant  carmine  color,  but  I  have  not 
detected  any  very  definite  structure  in  it.  The  color  is  so 
deep,  that  it  is  as  intense  as  carmine,  and  will  bear  an 
equal  magnifying  power  before  the  color  is  lost.  Under 
the  highest  power  of  the  microscope  I  can  only  make  out 
minute  cells.  Its'  intensity  of  color  is  the  prominent  fea- 
ture. 

(229.)  There  is  a  magnificent  fungus  of  a  brown  color, 
resembling  in  fact  oxide  of  iron  to  the  naked  eye,  which 
fungus  may  often  be  seen  in  the  interior  of  a  diseased  pota- 
toe, when  its  cavity  has  been  exposed  to  the  air.  Under 
the  microscope  it  is  found  to  be  a  perfect  forest,  with 
branches  resembling  in  some  degree  the  regularity  of  a 
pine-tree,  with  a  seed-vessel  at  top  of  each.  It  is  really 
and  truly  a  most  delightful  object  for  a  good  microscope. 
(Plate  iv.,  fig.  5.) 

(230.)  There  is  also  a  little  fungus  which  appears  to 
have  a  small  top,  which  a  microscope  breaks  up  into  a 
Medusa's  head.  I  think  it  is  the  same  as  that  to  which  the 
name  is  assigned  ;  but  I  must  refer  my  reader  to  the  faith- 
ful drawing  of  my  artist.  (Plate  m.,  fig.  5.) 

(231.)  Almost  every  stem  has  a  black  fungus  growing 
from  it,  which  to  the  naked  eye  gives  a  dotted  appearance 
to  it.  Under  the  microscope  fine  stems  are  seen  to  ema- 
nate from  it.  I  think  it  is  the  same  as  the  Protomyces.  I 
have  not  thought  it  therefore  worth  while  to  figure  Mar- 
tius's  drawing,  but  have  given  a  figure  from  one  of  my 
own  specimens.  This  fungus  is  also  frequently  to  be 
found  in  the  tuber.  (Plate  m.,  figs.  2,  3.) 


pi.'e. 


On  6'tene  fa  £ec. 


Printed  by  JST.'/MfoAfoK 


RELATION    OF    THE    DISEASE    TO    FUNGI.  59 

(232.)  One  very  delicate  fungus  is  frequently  to  be 
seen,  but  I  do  not  know  its  mode  of  fructification.  (Plate 
iv.,  figs.  2,  3.) 

(233.)  There  is  a  fungus  with  a  great  number  of  seed- 
vessels  at  the  top,  which  is  sometimes  to  be  met  with, 
growing  from  the  tubers  and  under-ground  stems,  which  I 
have  figured.  (Plate  iv.,  fig.  9.) 

(234.)  Many  of  these  fungi  move  about  when  placed 
under  the  microscope,  an  effect  which  probably  arises  from 
evaporation.  And  this,  I  am  inclined  to  believe,  must  have 
been  the  appearance  which  misled  some  one,  who  stated  in 
a  newspaper  article  that  he  imagined  these  fungi  to  be  of 
animal  origin. 

(235.)  One  of  the  last  fungi  which  attracted  my  atten- 
tion I  found  on  an  under-ground  stem.  It  presented  a 
lovely  beaded  form  (Plate  v.,  fig.  2).  And  I  have  also 
noticed  a  fungus  resembling  that  existing  in  the  scald  head 
of  human  beings  growing  from  dead  Aphides.  (Plate  m., 
fig.  7;  Plate  iv.,  fig.  1.) 

(236.)  Potatoes  in  a  diseased  condition  are  the  prey  of 
many  other  fungi ;  but  I  think  it  quite  needless  to  trouble 
the  reader  with  further  description.  In  Plates  in.  and  iv. 
I  have  figured  what  I  have  found ;  in  Plate  vi.  I  have 
copied  the  figures  of  Martius,  and  in  Plate  n.,  fig.  2,  and 
Plate  v.,  fig.  3,  Berkeley's  figures. 

(237.)  Doubtless  the  fungi  exercise  an  important  influ- 
ence upon  the  progress  of  the  disease,  although  they  most 
assuredly  have  not  the  power  of  producing  it.  In  fact, 
they  never  make  their  appearance  until  the  potatoe  plant 
has  been  previously  damaged,  and  until  some  portion  of  it 
is  already  dead.  I  have  tried  several  experiments  on  the 
inoculation  of  sound  potatoes  with  fungi,  but  the  result  has 


60  RELATION    OF    THE    DISEASE    TO    FUNGI. 

been  a  comparative  failure ;  and  sound  potatoes  would 
remain  amongst  others  abounding  in  numerous  fungi,  with- 
out being  injured. 

(238.)  When  the  plant  is  damaged  then  these  vegetable 
parasites  appear,  and  the  function  which  they  are  destined 
to  perform  is  highly  interesting,  and,  in  fact,  a  wonderful 
example  of  natural  economy ;  for  whilst  man  is  careless, 
and  allows  decomposing  bodies  to  send  forth  their  putrid 
exhalations,  and  even  buries  the  dead  in  the  midst  of  the 
houses  of  the  living,  and  allows  the  existence  of  open  drains 
and  unt rapped  sewers,  Nature,  when  not  interfered  with, 
amply  provides  against  the  occurrence  of  such  unhealthy 
and  offensive  conditions,  by  taking  effectual  means  to  re- 
move the  dead  material. 

(239.)  The  carrion  crow,  the  vulture,  and  the  jackall 
may  do  much, — the  maggot,  the  beetle,  and  the  wasp  may 
do  much, — towards  the  removal  of  dead  animal  matter ; 
yet  to  the  vegetable  parasite  is  left  the  duty  of  annihilating 
the  exhalations  of  putrefying  vegetables. 

(240.)  No  sooner  does  death  occur  than  fungi  grow : 
these  eat  up,  as  it  were,  the  soft  decaying  parts  as  fast  as 
they  rot ;  and  thus  is  inorganic  matter  converted  into  or- 
ganic,— thus  is  death  converted  into  life. 

(241.)  The  difference  between  gangrena  sicca  and  hu- 
mida  frequently  depends,  to  a  great  extent,  or  even  entirely, 
upon  these  parasites.  When  the  parasites  appear  they  dry 
up  the  potatoe,  absorb  the  decomposed  cells,  and  leave  the 
starch.  When  they  do  not  appear  the  tuber  is  far  more 
prone  to  become  putrid,  and  evince  the  properties  of  moist 
gangrene. 

(242.)  We  all  know  that  many  fungi  are  poisonous; 
and  I  ask,  what  surgeon  can  say  that  some  of  these  fungi 


ANIMAL     PARASITES.  61 

may  not  also  be  highly  deleterious,  either  to  all  persons, 
or  to  some,  as  the  result  of  idiosyncrasy.  In  my  opinion, 
it  would  be  a  prudent  course  to  reject  potatoes  which  are 
much  affected  with  fungi,  either  for  the  use  of  man  or 
beast. 

(243.)  I  have  viewed  with  great  interest  the  relation  of 
the  fungi  to  the  diseased  potatoe ;  I  have  seen  these  exqui- 
sitely beautiful  parasites  proceeding  from  that  which  would 
otherwise  have  been  offensive  and  disgusting ;  and  thus, 
when  the  diseased  tuber  becomes  unfit  to  nourish  the  body, 
the  parasite  that  emanates  from  its  decay  may  furnish  to 
the  mind  matter  for  observation  and  study  replete  with  in- 
terest. 


CHAPTER  X. 

RELATION    OF    GANGRENE    TO    ANIMAL    PARASITES. 

Numerous  species  of  insects  on  potatoe  plant  C244)  — Acarus  (245). 
Coccinella,  ichneumons,  flies  (247). — Aphis  (248). 

(244.)  THE  relation  of  this  gangrene  of  the  potato'e  to  ani- 
mal parasites  must  also  be  carefully  examined.  Flies  will 
sometimes  lay  their  eggs  in  rotten  potatoes,  various  infusorial 
animalcules  may  very  probably  be  produced  in  them,  and 
if  the  potatoe  plant  be  carefully  examined,  numerous  insects 
may  be  discovered  upon  it. 

(245.)  A  very  common  insect,  which  is  constantly  to  be 
seen  upon  tubers,  is  a  small  Acarus,  which  runs  about  the 


62  ANIMAL    PARASITES. 

potatoe  very  nimbly.  Martius  has  figured  it,  but  I  have 
given  an  illustration  from  one  which  I  captured  myself. 
There  is  no  reason  whatever  for  believing  that  it  causes 
the  malady.  Mr.  Ingall,  who  was  so  kind  as  to  make  the 
drawing,  remarks  that  this  little  fellow,  when  viewed  under 
the  microscope  travelling  among  the  dense  growth  of  the 
fungi,  put  him  in  mind  of  a  great  rhinoceros  trotting  about 
in  the  jungles.  He  certainly  does  present  a  very  extraor- 
dinary appearance.  (Plate  vn.) 

(246.)  There  is  a  little  yellow  insect  which  is  common 
upon  all  potatoes,  but  I  do  not  know  its  name.  It  appears, 
however,  to  me  to  be  quite  innocuous,  for  I  have  found  it 
upon  other  vegetables  which  have  been  quite  healthy  and 
uninjured.  In  the  "  Gardener's  Chronicle"  two  insects 
are  figured  which  have  been  supposed  to  have  an  influence 
on  the  disease — the  potatoe  thrip  and  the  Eupteryx  solanij 
but  I  see  no  evidence  to  suppose  that  they  cause  the 
malady. 

(247.)  Lady-birds  of  different  species  are  to  be  met  with 
in  great  profusion  on  the  potatoe  and  other  plants,  but  they 
are  animal  feeders,  and  can  therefore  do  no  harm.  Various 
ichneumons  also  in  great  numbers  are  to  be  found,  together 
with  many  dipterous  insects,  to  neither  of  which  can  any 
hurtful  quality  be  assigned. 

(248.)  If,  however,  we  carefully  examine  the  potatoe  at 
different  times,  we  find  another  insect,  an  Aphis,  in  great 
abundance  ;  which  Aphis  exerts  so  important  an  influence, 
that  I  must  devote  to  it  an  entire  chapter,  in  order  to  sepa- 
rate it  from  other  animal  parasites,  and  treat  it  with  that 
respect  which  its  formidable  powers  unfortunately  entitle 
it  to.  On  one  occasion  I  found  a  second  Aphis,  of  a  black 
color,  on  the  plant,  different  from  the  one  just  mentioned, 


\YV£^~va&» 


r 


Triited  fy  ff.  ff>  Johnson. 


APHIS    VASTATOR.  63 

but  this,  from  its  rare  occurrence,  cannot  produce  the  pre- 
sent universal  epidemic. 


CHAPTER  XI. 

APHIS    VASTATOR. 

Insect  on  the  potatoe  plant  (249 — 250)  ;  its  color  (252) ;  dimen- 
sions (256— 259).— Suctorial  apparatus  (260) ;  head  and  eyes 
(261) ;  abdomen  and  tubercles  (262);  pupa  (263) ;  imago,  or  per- 
fect insect  (264);  named  "  vastator,"  and  why  (265). — Curtis' 
description  (266).— Astonishing  fecundity  (267 — 269).— Continu- 
ance of  the  species  (270 — 273). — Mode  of  attack  on  the  plant 
(274,  275).— Restlessness  of  the  insect  (276— 278).— Flight  of 
the  insects  (281,  282).— Progress  of  the  mischief  (283—285).— 
Action  on  different  varieties  (286, 287). — Effect  of  moisture  after 
attack  (288,  289). — Attack  at  different  ages  of  the  plant  (290, 
291).— Relation  of  the  disease  to  this  insect  (292—294). 

(249.)  UPON  a  minute  examination  of  the  leaves  and 
stalk  of  a  potatoe  plant,  a  small  insect  will  be  found, 
feeding  either  alone  or  in  company  with  others,  and  prin- 
cipally on  the  under  surface  of  the  leaf. 

(250.)  This  insect  is  generally  seen  perfectly  stationary, 
and  might  easily  elude  observation,  from  being  in  the 
early  stage  of  m  its  growth  of  a  color  not  widely  differing 
from  that  of  the  leaf.  If  attentively  examined  with  a  mag- 
nifying-glass,  it  will  be  seen  to  be  adhering  to  the  plant, 
and  remaining  in  a  state  of  repose,  with  its  antennee  reflex- 
ed  over  its  back,  and  a  sort  of  proboscis  applied  to  the  leaf. 
(Plates  vm.  and  ix.) 


64  APHIS    VASTATOR. 

(251.)  If  the  insect  be  touched,  it  will  be  found  that  it 
adheres  pretty  firmly  to  the  leaf  by  its  suctorial  apparatus, 
and  that  it  requires  one  or  two  seconds  to  disengage  itself 
from  its  position. 

(252.)  The  color  of  this  little  insect  is  various:  in  very 
early  life  its  body  is  nearly  transparent ;  later  it  is  of  an 
olive  color  ;  at  other  times  it  is  grass  green,  and  at  a  later 
period  it  may  be  found  to  be  of  a  reddish  color. 

(253.)  We  have  in  this  little  insect  a  parasite  which 
derives  its  nourishment  from  the  plant  by  sucking  the 
juices,  which  operation  it  effects  by  means  of  the  very 
curious  apparatus  which  I  shall  hereafter  describe. 

(254.)  This  insect  is  found  in  three  stages  of  exist- 
ence,— the  larva,  the  pupa,  and  the  imago,  or  perfect 
winged  insect ;  in  all  of  which  states,  like  its  congeners,  it 
feeds,  remains  active,  and  probably  multiplies. 

(255.)  From  an  examination  of  its  different  states,  we 
know  that  it  not  only  belongs  to  the  family  of  Aphida,  but 
must  be  classed  under  the  genus  Aphis. 

(256.)  The  Aphis  vastator  when  full  grown  is  about  the 
tenth  of  an  inch  long,  and,  as  I  have  before  mentioned,  the 
color  is  white,  olive  green,  brown,  or  inclined  to  red. 

(257.)  The  Antennae  are  seven-jointed  ;  they  are  nearly 
as  long  as  the  body,  and  sometimes  even  longer.  The 
subjoined  measurement  of  a  specimen,  which  I  take  to  be 
an  adult  apterous  female,  shows  the  dimensions  of  the 
various  parts  of  the  insect  in  lOOOths  of  an  inch: — 

Length  of  body  from  base  of  antennae  to  apex  of  abdomen  106 

Greatest  breadth  of  body             -            -            --,  55 

Breadth  of  head  between  the  eyes    -                          -  12 

Antei-ior  femur               -        '  ;S-   -.                     -  22 

"         tibia            -           **            *  ~           -            -  36 


PL  8. 


0n  Stone  'Ay  Grt*,tMe»/r, 


APHIS    VASTATOR. 


65 


Anterior  tarsus  -  -        r-^^Vi 

Posterior  tibia 
Abdominal  spines 
Length  of  rostrum 
Antennae,  1st  articulation 

2d 

3d  "       - 

4th 
-  5th 

6th 

7th          "       - 
In  a  winged  specimen  the  wing  measured  about 


0 

55 
24 
26 

4 

3 

20 
164 
14 

5 

19 
128 


(258.)  Considerable  variation  is  observed  in  the  total 
length  of  the  antennae  in  different  specimens,  the  reason  for 
which  I  do  not  know.  In  all  cases,  however,  they  are 
long  in  this  species,  and  the  relative  length  of  the  different 
joints  forms  an  important  characteristic. 

The  following  measurements  give  the  comparative 
lengths  of  the  articulations  of  the  antennae  in  different 
specimens  of  this  insect: — 


1. 

2. 

3. 

4. 

5. 

6. 

7. 

TOTAL 

4 

3 

18 

15 

12 

6 

20 

78 

3 

2* 

9 

7 

9 

4 

13 

474 

2* 

3 

16 

13k 

10i 

5 

19 

69£ 

4 

3 

20 

16 

L4 

5 

19 

81 

(259.)  When  the  creature  is  at  rest  and  feeding  quietly, 
the  antennas  lie  reflexed  over  his  back  ;  and  this  posture 
is  well  shown  in  the  diagram.  (Plate  vin.,  fig.  4.) 
When,  however,  he  is  roving  about,  he  carries  them  ex- 
tended before  him,  apparently  to  feel  or  smell  by  their 
assistance. 


66  APHIS    VASTATOR. 

(260.)  The  rostrum  is  about  one  fourth  as  long  as  Ihe 
body,  and  contains  a  fine  apparatus  for  piercing  the  leaf 
and  walls  of  the  cells.  This  instrument  when  open  pre- 
sents three  diverging  delicate  piercers,  one  of  which 
answers  to  the  tongue  and  the  other  to  the  jaws  of  insects. 
(Plate  ix.,  fig.  2 ;  Plate  vm.,  fig.  7,  a,  ~b,  c-) 

(261.)  The  head  is  very  distinct  in  its  form,  and  has 
fine  spines  upon  it.  The  eyes  are  red  or  black,  and  so 
strongly  colored  that  they  may  be  seen  through  the  mem- 
brane which  envelopes  the  insect  before  it  is  born. 

(262.)  The  abdomen  is  very  angular  when  the  creature 
is  walking  about,  and  is  furnished  towards  its  extremity 
with  tubercles,  which  extend  posteriorly  as  far  as  the  apex 
of  the  abdomen.  These  tubercles  are  hollow,  and  contain 
a  peculiar  matter  in  the  interior. 

(263.)  In  the  pupa  state  it  has  rudimentary  wings, 
which  grow  for  a  certain  time,  when  the  creature  casts 
its  skin,  and  comes  out  a  winged  specimen.*  (Plate  vm., 
fig.  4.) 

(264.)  The  winged  insect  has  four  wings,  which  are 
carried  in  the  same  posture  as  they  are  by  all  other 
Aphides.  With  these  wings  it  is  cabable  of  flying  to 
great  distances,  but  it  is  generally,  except  when  on  flight, 
a  lazy  creature  in  its  final  or  perfect  state,  and  not  very 
prone  to  fly  away  for  slight  causes.  (Plate  ix.,  figs.  1 
and  4.) 

(265.)  After  a  careful  comparison  of  this  insect  with  all 
the  other  Aphides  of  which  descriptions  have  been  publish- 

*  I  do  not  know  exactly  how  many  times  the  insect  casts  its  skin, 
but  I  am  inclined  to  think  that  this  operation  is  performed  at  least 
three  or  four  times.  * 


APHIS    VASTATOR.  67 

ed,  I  found  that  it  was  identical  with  one  known  heretofore 
to  infest  the  turnip,  and  which  is  called  by  Curtis  the 
Aphis  rapce.  I  found,  however,  that  the  use  of  this  name 
was  so  embarrassing,  and  led  to  such  confusion,  from  the 
insect  feeding  upon  the  turnip  in  common  with  other 
Aphides,  itself  too  attacking  twenty  or  thirty  different 
plants,  that  I  decided  to  meet  the  difficulty  by  describing 
it  under  a  new  title ;  and  having  discovered  that  this  pest 
is  a  great  destroyer  of  human  food,  a  waster  of  our  best 
provisions,  I  have  therefore  termed  it  the  vastator,  or 
destroyer. 

(266.)  Having  determined  that  the  vastator  is  the  same 
insect  as  the  Aphis  rapse  of  Curtis,  I  make  no  apology  for 
transcribing  his  description  of  the  animal,  which  is  as 
follows : — 

"  Male  ochraceous :  horns  moderately  long,  setaceous, 
fuscous,  two  first  joints  black,  third  ochraceous  at  the  base  ; 
head  blackish ;  collar  ochraceous  and  brown ;  disc  of 
thorax  shining  black ;  abdomen  greenish ;  the  spiracles 
or  breathing  pores  brown ;  tubes  long,  slender,  ochraceous 
at  the  tip  ;  the  apical  process  of  the  body  ochraceous  also  ; 
wings  iridescent,  the  nervures  light  brown  ;  stigmatic  spot 
long  and  yellowish ;  apical  cell  somewhat  oval ;  furcate 
cells  elongate,  trigonate ;  terminal  very  short ;  tips  of 
thighs,  shanks,  feet,  and  claws  black.  Female  light 
green,  shagreened :  horns  fuscous,  except  at  the  base  ; 
eyes,  tips  of  shanks  and  feet  black." 

I  do  not  know  whether  this  Aphis  has  ever  been  named 
before  the  time  of  Curtis,  and  in  fact  the  description  of 
Aphides  by  the  older  writers  is  so  imperfect  that  even 
their  figures  would  answer  for  any  insect  of  the  same 
genus. 


68 


APHIS    VASTATOR. 


(267.)  The  Aphis  vastator  comes  upon  the  potatoe  plant 
in  the  winged  state,  and  there  brings  forth  its  young  alive. 
These  generally  prefer  at  first  a  large  and  rather  debili- 
tated leaf.  After  a  short  time  the  insect  brings  forth  other 
young,  which  young  themselves  reproduce  without  any 
connexion  with  individuals  of  the  other  sex  ;  and  thus  from 
a  single  specimen  a  plant  may  speedily  become  covered 
with  the  insects. 

(268.)  It  has  been  proved  by  Reamur,  that  in  five  genera- 
tions one  Aphis  may  be  the  progenitor  of  5,904,900,000 
descendants ;  and  it  is  supposed  that  in  one  year  there  may 
be  twenty  generations.  I  know  no  reason  why  the  vastator 
should  be  less  prolific  than  its  congeners  ;  and  the  rapid 
rate  at  which  I  have  seen  them  produced  would  in  some 
degree  justify  the  conclusion  that  they  are  not  at  all 
behind-hand  in  this  respect. 

(269.)  1  have  repeatedly  seen  both  winged  and  apterous 
specimens  produce  their  young  alive,  though  up  to  the 
present  time  I  believe  that  1  am  conversant  only  with 
females.  I  do  not  certainly  know  the  males  of  the  vasta- 
tor. It  is  stated,  however,  that  the  males  of  all  Aphides 
may  be  either  winged  or  apterous,  and  that  the  females  may 
produce  young  for  nine  generations  without  any  union  with 
the  males. 

(270.)  As  far  as  my  own  observations  are  concerned  the 
vastator  always  appears  as  a  viviparous  creature  ;  but  I  do 
not  as  yet  know  how  it  is  propagated  throughout  the  year. 

(271.)  Entomologists  state  that  in  autumn  the  females 
lay  eggs,  instead  of  bringing  forth  their  young  alive  j  but 
this  I  have  not  yet  myself  had  an  opportunity  of  observing. 
It  is,  however,  a  very  important  circumstance,  and  I  hope 


APHIS    VASTATOR.  69 

eventually  to  make  myself  conversant  with  the  fact,  as  it 
has  a  bearing  upon  the  future  course  of  the  potatoe  disease. 

(272.)  I  have  found  eggs  apparently  of  other  Aphides 
upon  the  couch-grass.  I  have  also  given  a  figure  of  the 
young  Aphis  enveloped  in  a  membrane,  and  in  a  state  just 
ready  to  come  into  the  world.  This  therefore  shows  me 
what  sort  of  an  egg  we  may  expect  to  find,  if  the  creature 
ever  lays  one.  (Plate  vin.,  fig.  1.) 

(273.)  The  desired  information  probably  will  resolve 
itself  into  three  questions :  Does  the  vastator  lay  eggs 
which  hatch  in  spring  ?  Does  it  hybernate,  and  come  out 
again  in  the  spring  ?  Does  it  continue  to  propagate  not- 
withstanding cold,  frost,  and  rain  ?  Up  to  November  4th, 
I  have  found  the  creature  bringing  forth  its  young  alive. 

(274.)  The  vastator  begins  at  the  larger  leaves  of  the 
potatoe  plant,  which,  after  a  short  time,  becoming  injured 
by  the  abstraction  of  the  sap,  die  either  partially  or  entirely. 
In  this  case  the  insect  follows  up  the  leaves  till  only  a  few 
on  the  top  of  the  plant  are  left. 

(275.)  This  operation  is  not  going  on  in  one  plant  alone, 
it  is  generally  progressing  in  every  plant  in  the  field  at  the 
same  time  ;  leaf  by  leaf  all  dying,  till,  as  I  have  just  stated, 
a  few  only  of  the  apical  leaves  are  left. 

(276.)  Regarding  the  mode  in  which  a  whole  field 
becomes  attacked,  I  may  observe  that  the  vastator  is  a  sad 
rover :  he  may  frequently  be  seen  travelling  up  and  down 
the  potatoe  plant  with  his  antennae  waving  before  him, 
as  though  he  were  uneasy,  and  did  not  quite  like  his 
situation. 

(277.)  From  this  restlessness,  coupled  with  the  fact  that 
the  insect  is  generally  diffused  over  a  field,  I  am  inclined 
to  believe  that  the  potatoe  is  not  the  most  agreeable  food  to 


70  APHIS    VASTATOR. 

the  vastator,  and  I  do  not  think  it  thrives  quite  so  well  upon 
it  as  upon  plants  which  I  shall  hereafter  describe. 

(278.)  So  restless  an  insect  is  it,  that  when  1  have 
placed  it  upon  one  plant  in  my  sitting-room,  where  other 
plants  were  also  present,  I  generally  found  that  part  of  the 
creatures  had  crawled  to  the  other  plants ;  in  fact,  I  have 
observed  that  my  specimens  have  wandered  all  over  my 
library. 

(279.)  When  these  little  creatures  crawl  over  the  skin, 
they  produce  a  tickling,  too  exaggerated  to  be  pleasant ; 
in  fact,  their  crawling  is  attended  with  a  sensation  which 
is  quite  painful.  These  little  fellows  look  very  majestic, 
marching  with  their  antennae  extended  before  them. 

(280.)  When  the  creature  first  appears,  he  is  to  be  found 
sparingly  distributed  over  the  larger  leaves  of  the  plant ; 
but  when  the  greater  part  of  the  plant  is  destroyed,  and  the 
insect  has  multiplied,  great  numbers  may  be  found  on  a 
single  leaf,  as  though  they  were  determined  utterly  to 
annihilate  it.  The  leaflet  figured  contained  about  eighty 
insects  upon  it. 

(281.)  They  then  become  partially  starved,  enter  into 
the  pupa  state,  cast  their  skins,  and  emerge  as  winged 
insects,  when  they  fly  away,  and  leave  no  trace  behind 
them  save  and  except  the  destruction  of  the  plant,  and 
some  few  specimens  which  have  been  injured  by  the 
ichneumons.  This  fact  is  exceedingly  remarkable,  for  on 
watching  a  piece  of  land,  I  have  found  scarcely  one  of  the 
insects  to  be  left  behind,  after  the  greater  part  had  had 
their  wings  developed  and  had  flown  away.  I  think  that 
from  the  period  of  birth  it  requires  about  a  fortnight  before 
the  Aphis  obtains  wings  and  flies  away. 

(282.)  The  Aphides  over  a  whole  field  take  wing  about 


APHIS    VASTATOR.  71 

the  same  period,  and  then  a  vast  cloud  of  them  is  formed, 
which  flies  to  some  new  locality,  there  to  renew  its  ravages. 
This  cloud  appears  in  the  distance  in  the  form  of  a  mist. 
I  have  seen  the  whole  air  filled  with  the  flying  insects.  I 
have  even  observed  the  creatures  to  settle  upon  myself  in 
the  streets  in  the  centre  of  London  ;  and,  in  fact,  wherever 
I  have  been,  there  have  I  seen  the  destroyer  winging  its 
way  to  commit  further  destruction. 

(283.)  When  the  plant  is  freed  from  its  pest  it  will  some- 
times grow,  and  send  forth  new  roots  to  nourish  the  stem, 
and  the  haulm  will  thus  retain  much  of  its  vigor.  If,  how- 
ever, the  plant  has  been  once  seriously  damaged,  it  will 
perish  without  a  second  attack  of  the  Aphides,  upon  the 
principle  which  I  have  heretofore  pointed  out,  namely,  that 
a  diseased  potatoe  will  grow  a  diseased  plant. 

(284.)  When  the  vastator  attacks  the  potatoe,  each  leaf 
is  separately  destroyed,  and  the  mischief  may  extend  to  the 
stalk  and  root.  In  many  cases  the  progress  of  the  disease 
is  at  first  from  above  downwards. 

(285.)  The  effect  of  the  destroyer  may  be  watched  upon 
a  sprig  of  potatoe  placed  in  water  :  we  then  see  very  clearly 
the  mode  in  which  the  leaf  dies  and  withers  up.  The  vas- 
tator passes  over  a  field  like  a  blast ;  it  damages  the  root, 
lessens  the  vital  power  of  the  plant,  and  the  insect  then  as- 
sumes the  winged  state  and  flies  away. 

(286.)  This  vastator  does  not  commit  the  same  amount 
of  mischief  upon  every  kind  of  potatoe.  It  dislikes  those 
leaves  where  moisture  is  to  be  found  on  the  under  surface 
in  the  morning ;  and  thus,  according  to  the  state  of  the 
plant,  it  passes  over  with  greater  or  less  rapidity. 

(287.)  The  wild  potatoe  at  Chelsea  appears  especially 
to  resist  its  deleterious  action,  for  although  I  found  thou- 


72  APHIS    VASTATOR. 

sands  upon  the  large  leaves,  yet  they  did  not  destroy  it  to 
half  the  extent  that  they  would  have  done  if  they  had  at- 
tacked some  of  the  more  highly"  cultivated  varieties  of  pota- 
toe,  and  I  am  informed  that  all  the  tubers  up  to  November 
3d  were  quite  sound. 

(288.)  When  the  insect  has  damaged  the  leaf  of  the 
plant,  it  is  much  influenced  by  wet  weather :  a  shower  of 
rain  will  fill  the  stems  with  water :  and  in  consequence  of 
the  solid  portion  having  been  taken  away  by  the  insect, 
the  moisture  cannot  cause  the  rapid  growth  of  the  plant 
which  should  take  place  under  such  circumstances. 

(289.)  The  sap  being  thus  in  too  fluid  a  condition,  acts 
prejudicially,  and  the  plant  rots  at  the  collar,  the  under- 
ground stems,  various  parts  of  the  upper  stem,  the  leaves, 
the  fruit.  After  this  disorganization  all  the  effects  which 
I  have  described  when  treating  of  the  disease  take  place. 

(290.)  The  amount  of  injury  committed  by  the  destroyer 
is  in  a  great  measure  proportionate  to  the  period  of  the 
growth  of  the  plant  at  which  it  attacks  it.  If  it  attack  it  in 
the  early  part. of  the  year,  the  plant  is  killed  before  the 
tuber  is  formed,  and  the  worst  damage  is  done ;  if  at  a 
later  period,  the  starch  is  diminished  in  quantity;  and  if  it 
attack  the  plant  after  the  tubers  are  completely  developed, 
then  the  creature  can  do  but  little  injury. 

(291.)  It  is  from  this  cause  we  find  that  in  the  districts 
where  the  plant  was  affected  in  July,  it  did  so  much  more 
damage  than  when  it  commenced  its  ravages  in  August. 

(292.)  The  first  appearance  of  the  disease  in  a  healthy 
and  previously  undamaged  plant  is  always  subsequent  to 
the  visit  of  the  destroyer ;  and  the  amount  of  the  disease, 
ccRteris  paribus,  is  directly  proportionate  to  the  number  of 
insects  which  take  away  the  vital  fluid  of  the  plant. 


TURNIP    DISEASE.  73 

(293.)  In  subsequent  chapters  I  shall  prove  that  these 
important  facts  have  their  analogies ;  for  I  shall  show  that 
the  same  disease  is  produced  by  the  same  insect  in  different 
plants ;  and  also  that  other  species  may  produce  similar 
disease  in  the  plants  on  which  they  feed. 

(294.)  With  respect  to  the  potatoe  plant,  I  have  here  to 
enforce  that  the  winged  creatures  settle  upon  the  larger  or 
more  vigorous  leaves  first,  and  produce  young  ones,  which 
rapidly  multiply.  These  suck  the  juices  of  the  plant, 
causing  the  plant  to  die  locally.  They  also  cause  the 
under-ground  stem  to  rot  at  the  collar,  and  thus  effect  the 
destruction  of  the  entire  plant,  by  completely  separating  the 
haulm  from  the  roots. 


CHAPTER  XIL 


TURNIP    DISEASE. 

White  turnjps,  method  of  attack  thereon  (296,  297).— Effects  of  the 
attack  (298— 301).— Spiral  vessels  (302,  303).— Effluvia  from  rot 
(304).— Effects  of  time  (305,  306).— Fungi  (307).— Aphis  bras- 
sicae,  description  of,  (309,  310);  its  habits  (311,  312). — Swede 
turnip  (316).— Conclusion  (318). 

(295.)  BESIDES  the  potatoe  the  vastator  attacks  other 
plants ;  a  fact  which  is  important  not  only  on  account  of 
the  value  of  the  plants  which  are  destroyed,  but  also  as 
showing  that  the  same  insect  commits  similar  ravages  on 
other  plants. 

4 


74  TURNIP    DISEASE. 

(296  )  The  plant  attacked  which  is  next  in  importance 
to  the  potatoe  is  the  common  white  turnip.  In  this  case 
the  perfect  insect  commences  its  attacks  by  settling  upon 
the  larger  leaves  of  the  turnip  when  the  plant  is  about  four 
inches  high,  and  there  producing  its  young.  Sometimes, 
however,  it  attacks  it  at  an  earlier  period  of  its  growth, 
even  when  in  the  seed  leaf;  and  I  have  this  day  observed 
it  in  the  Circus  garden  on  plants  barely  out  of  the  seed 
leaf. 

(297.)  These  young  ones  continue  to  produce  with  great 
rapidity,  and  spread  from  leaf  to  leaf,  until  the  whole  plant 
is  implicated.  The  larger  leaves  which  were  first  attacked 
die  first,  and  the  others  in  succession,  till  the  whole  plant 
becomes  disorganized. 

(298.)  Sometimes  the  plants  affected  present  a  curious 
appearance  at  the  root,  called  "fingers  and  toes;"  in  fact 
the  root  becomes  diseased,  and  these  fingers  and  toes  are 
multiplications  of  the  root,  and  are  thrown  out  by  an  effort  of 
nature  in  order  to  compensate  for  the  injury'done  to  the  main 
root  or  turnip.  In  this  state  the  turnip  dies,  becomes  with- 
ered and  dried  up,  forming  an  example  of  gangrena  sicca, 
analogous  to  the  dry  gangrene  of  the  potatoe. 

(299.)  The  manner  in  which  the  turnip  dies  is  quite 
similar  to  that  in  the  case  of  the  potatoe ;  a  portion  of  the 
leaf  may  go, — a  portion  of  the  stalk  supplying  nourish- 
ment to  the  plant  may  die, — or,  lastly,  the  root  or  whole 
plant  may  perish. 

(300.)  If  the  bulk  is  fully  formed,  and  the  insects  con- 
tinue to  prey  upon  the  leaf,  the  collar  of  the  turnip,  that  is, 
the  joining  point  of  the  leaves  and  the  root,  begins  at  last  to 
rot,  and  after  the  lapse  of  a  short  time,  if  the  leaves  are 


TURNIP   DISEASE.  75 

held  in  the  hand  and  very  slightly  pulled,  they  will  com- 
pletely  separate  from  the  bulb. 

(301.)  This  rot  at  the  root  does  not  take  place  in  very 
young  turnips ;  it  is  requisite  that  they  should  have  at- 
tained a  certain  growth  before  that  appearance  is  exhibited. 
The  leaf,  however,  does  not  require  that  age,  as  I  have 
seen  young  leaves  curl,  turn  brown,  and  die  at  a  very 
early  period  of  their  growth,  though  generally  they  attain 
a  fair  size  before  that  occurs. 

(302.)  If  a  turnip  be  examined  in  a  state  not  so  far  ad- 
vanced in  decomposition  as  in  the  instance  which  I  have 
already  described,  it  will  be  found  to  present  a  remarkable 
analogy  with  the  rotten  potatoe  ;  and  the  spiral  vessels 
certainly  do  appear  to  have  some  influence  on  the  malady, 
probably  from  the  excess  of  oxygen  peculiar  to  that  part 
of  the  bulb  favoring  the  decay.  (Plate  vn.,  fig.  2.) 

(303.)  In  the  turnip,  then,  the  disease  appears  at  the 
spiral  vessels,  and  extends  inwards  towards  the  centre. 
The  part  between  the  spiral  vessels  and  the  exterior  does 
not  seem  so  prone  to  take  on  the  malady. 

(304.)  During  the  progress  of  the  disease  the  most 
offensive  odor  is  exhaled  from  the  plant.  It  is  much  worse 
than  the  effluvia  emanating  from  the  diseased  potatoe  ;  and, 
in  fact,  when  the  turnip  root  is  decayed,  it  iamore  damaged 
than  the  potatoe.  In  the  turnip  there  is  no  starch  to  be  left, 
and  it,  therefore,  becomes  a  mere  mass  of  offensive  putre- 
faction. 

(305.)  From  my  observations,  I  should  infer,  that  if  we 
left  turnips  as  long  in  the  ground,  comparatively  with  the 
development  of  the  plant,  as  we  do  potatoes,  the  disease 
would  be  found  to  be  equally  extensive ;  but  the  fact  is, 
we  use  turnips  at  an  earlier  period  of  the  growth  of  the 


76  TURNIP    DISEASE. 

plant,  and  the  disease  does  not  appear  to  manifest  itself 
very  decidedly  till  the  vegetable  is  depositing  woody  fibre. 

(306.)  We  leave  potatoes  in  the  ground  till  the  plant 
has  run  its  course,  has  fruited  and  exhausted  itself;  whilst 
the  turnip  is  employed  in  the  first  period  of  its  growth, 
when  it  is  but  half  developed,  and  before  it  has  fruited  and 
become  exhausted.  Notwithstanding  this  difference,  how- 
ever, the  vastator  destroys  great  masses  of  turnips,  and 
causes  them  so  to  rot  as  to  be  totally  unfit  for  use. 

(307.)  The  turnip  plant  exhibits  fungi,  which  come 
upon  the  leaf  after  the  attack  of  the  vastator,  and  thus  we 
have  another  analogy  between  the  potatoe  and  turnip  dis- 
ease. Berkeley  has  figured  a  fungus  which  he  found  on 
the  Swedish  turnip. 

(308.)  The  vastator  generally  feeds  upon  the  under 
surface  of  the  turnip  leaf,  for,  being  a  restless  insect,  im- 
patient of  the  slightest  intrusion,  it  generally  crawls  to  the 
under  side.  In  a  sitting-room  they  feed  indifferently  upon 
either  side  of  the  leaf. 

(309.)  There  is  another  Aphis  which  feeds  commonly 
upon  the  turnip,  and  which  is  also  highly  destructive  to  it, 
but  which  we  must  be  careful  to  distinguish  from  the  vas- 
tator. This  insect,  which  is  apparently  the  Aphis  brassi- 
cse,  may  be  known  from  the  vastator  by  its  whiter  color, 
by  its  shorter  antennae,  by  its  short  abdominal  tubercles, 
and  by  its  more  gregarious  habit,  the  insects  feeding  in 
companies  very  closely  together,  like  a  flock  of  sheep,  and 
seldom  jnoving  from  their  situation.  The  winged  speci- 
mens may  often  be  found  dead  in  the  midst  of  their  off- 
spring. 

(310.)  The  Aphis  brassicse  presents  the  peculiar  ros- 
trum and  suctorial  apparatus  which  I  have  before  described 


TURNIP    DISEASE.  77 

as  appertaining  to  the  vastator,  from  which  it  is  a  different 
species,  though  also  a  true  Aphis.  The  solitary  habits  of 
the  vastator,  and  the  gregariousness  of  the  brassicse,  form 
strong  distinctive  characters  in  addition  to  those  of  form  and 
color. 

(311.)  The  first  specimens  which  make  their  appear- 
ance on  the  plant  are  winged  insects,  which  produce  small 
larvae ;  these  rapidly  grow*,  and  produce  others.  As  long 
as  the  plant  is  in  a  vigorous  state  the  insect  is  transparent ; 
afterwards  it  becomes  olive-green  •  and  when  the  plant 
begins  to  suffer  from  its  ravages  the  insect  turns  reddish 
brown,  takes  the  pupa  form,  and  finally  emerges  with 
wings.  I  have  a  turnip  plant  growing  in  a  glass,  which 
has  been  nearly  destroyed  by  the  insect,  and  during  the 
last  two  days  it  has  been  curious  to  observe  how  fast  the 
insects  have  assumed  the  winged  state  to  fly  away  before 
their  supply  of  food  entirely  fails  them  by  the  perishing  of 
the  plant. 

(312.)  We  thus  perceive  that  the  power  of  reproduc- 
tion is  proportionate  to,  and  is  indeed  controlled  by,  the 
quantity  of  food ;  and  when  the  food  diminishes,  the  crea- 
ture, instead  of  reproducing,  obtains  wings  and  flies  away, 
to  extend  its  species  in  more  distant  places.  And  here  we 
have  one  of  those  instances  with  which  natural  history 
abounds,  of  the  wonderful  resources  of  nature.  Those 
animal  powers  of  the  insect,  which,  as  long  as  food  was 
abundant,  were  employed  in  extending  its  progeny,  are 
afterwards,  when  the  supply  becomes  deficient  and  preca- 
rious, turned  into  a  new  channel,  the  result  of  which  alte- 
ration is  the  development  of  wings.  The  little  creature  is 
not  left  by  nature  to  perish  in  the  wilderness  which  itself 


78  TURNIP    DISEASE. 

has  made,  but  is  thus  furnished  with  efficient  means  to 
bear  it  away  to  more  hospitable  places. 

(313.)  To  ascertain  beyond  all  doubt  that  the  vastator 
of  the  potatoe  is  the  same  insect  as  the  vastator  of  the  tur- 
nip, I  have  placed  those  obtained  from  the  turnip  on  the 
potatoe,  and  those  from  the  potatoe  on  the  turnip.  From 
this  experiment  I  found  that  either  plant  was  indifferent  to 
them ;  but  I  noticed  that  the  potatoe  vastator  seemed  to 
like  the  turnip  better  than  those  from  the  turnip  liked  the 
potatoe. 

(314.)  I  could  not  help  observing  how  much  more  sta- 
tionary and  tranquil  this  insect  became  when  placed  upon 
the  turnip  ;  he  appeared  to  have  got  just  what  he' wished 
for,  and  to  be  in  a  high  state  of  self-satisfaction,  not  wan- 
dering about  in  search  of  anything  better  suited  to  his 
taste  :  whereas,  when  on  the  potatoe,  he  never  seemed  to  be 
quite  comfortable,  but  would  be  strolling  about  and  trot- 
ting over  the  leaf,  instead  of  sitting  down  at  once  seriously 
to  his  victuals. 

(315.)  The  most  minute  microscopical  examination  was 
made  of  the  vastator  from  the  two  plants,  but  without 
detecting  the  slightest  difference  of  structure. 

(316.)  The  Swede  turnip  is  also  injured  by  the  vasta- 
tor ;  it  is,  however,  attacked  far  more  sparingly  by  this 
species,  and  to  a  far  greater  extent  by  the  Aphis  brassicse. 
It  is  difficult  to  isolate  the  effect  produced  by  the  two 
species,  and  therefore  I  did  not  attempt  the  investigation. 

(317.)  A  turnip,  when  it  is  growing  very  vigorously, 
seems,  as  it  were,  to  throw  off  the  insect,  or  in  fact  to 
grow  quicker  than  the  creature  multiplies ;  the  root  gets 
the  better  of  the  attack,  and  the  insect  does  not  injure  it  to 
such  an  extent. 


BEET,    SPINACH,    AND    CARROT    DISEASE.  79 

(318.)  From  the  above  account  of  the  turnip  disease, 
we  see  in  the  first  place  that  the  white  turnip  is  visited 
with  a  malady  identical  in  every  respect  in  character  with 
that  of  the  potatoe  :  the  leaf  dies,  the  stalk  dies,  the  root 
dies,  and  the  two  phenomena  of  gangrene,  the  dry  and 
wet,  are  shown.  In  the  second  place,  the  same  insect  is 
found  upon  the  plant  previously  to  this  change  taking 
place  ;  and,  lastly,  the  disease  appears  at  those  parts  of  the 
plant  which  the  creature  punctures.  Our  argument  is, 
therefore,  cumulative,  for  two  plants  are  attacked  by  the 
same  insect,  and  this  attack  is  followed  by  the  same 
disease. 


CHAPTER  XIII. 

BEET,    SPINACH,    AND    CARROT    DISEASE. 

Beet  attacked  by  the  Aphis  (319). — Mode  in  which  the  disease  pro- 
gresses (320— 322).— Number  of  insects  on  a  plant  (323).— An- 
other species  of  Aphis  (324). — Spinach  attacked  (325). — Effects 
of  attack  (320).— Action  of  disease  (327). — Effect  of  rain  on  dis- 
eased plant  (328).— Carrot  subject  to  the  disease  (329).— Opera- 
tion of  disease  upon  it  (330,331). — Disease  identical  in  all  plants 
attacked  (332). 

(319.)  THERE  is  another  plant  of  very  great  importance 
which  this  destructive  creature  infests,  and  that  is  the 
beet-root,  including  the  mangel-wurzel  and  all  its  other 
varieties.  The  leaves  of  the  beet  are  frequently  to  be 
seen  completely  loaded  with  this  animal. 

(320.)  There  is  a  small  field  of  beet  in  the  Kentroad, 


80  BEET,    SPINACH,    AND    CARROT    DISEASE. 

where  the  large  leaves  were  totally  covered  by  a  living 
mass  of  these  creatures.  In  some  plants  portions  only  of 
the  leaf  were  destroyed  ;  in  others  more  extensive  mis- 
chief was  effected  ;  and  in  those  plants  where  the  malady 
had  proceeded  still  further,  the  gangrene  was  propagated 
from  the  leaf  down  the  stalk,  and  so  on  to  the  crown  of 
the  root,  which  last  finally  became  affected.  The  insect 
destroys  leaf  after  leaf,  till  in  some  cases  the  entire  plant 
is  killed.  The  growth  of  the  plant  is  of  course  materially 
interfered  with  by  the  stripping  off  of  its  leaves,  and  in 
several  instances  I  observed  that  the  root  was  totally 
rotten.  When  the  root  is  rotten  the  disease  appears  mostly 
close  to  the  spiral  vessels  ;  and,  from  the  number  of  these 
vessels  in  this  plant,  the  whole  speedily  becomes  affected. 
(Plate  vii.,  fig.  6.) 

(321.)  In  this  plant  I  observed  a  fact  which  I  have 
noticed  in  many  other  instances  ;  viz.  that  the  greatest 
amount  of  mischief  is  produced  in  the  plant  at  that  period 
of  its  growth  when  we  may  expect  fibre  to  be  deposited. 

(322.)  For  this  reason  the  whole  plant  seemed  always 
to  be  more  seriously  deranged  when  it  had  prematurely 
run  to  seed  ;  the  small  leaves  of  the  stem  were  more 
seriously  destroyed  ;  the  stalk  was  more  injured,  and  the 
whole  plant  died. 

(823.)  I  do  not  pretend  to  have  counted  the  number  of 
the  vastator  which  may  be  found  occasionally  on  a  single 
plant ;  but  I  should  say,  confidently,  that  not  less  than 
30,000  or  40,000  may  be  sometimes  found  on  a  large 
specimen. 

(324.)  There  is  another  species  of  Aphis,  a  little  black 
rascal,  which  also  infests  this  plant,  but  1  have  not  found 
it  to  a  very  great  extent. 


BEET,    SPINACH,    AND    CARROT    DISEASE.  81 

(325.)  The  gangrene  also  attacks  the  spinach ;  and 
this  plant  requires  attentive  consideration,  because  it 
appears  to  be  very  susceptible  of  injury. 

(326.)  When  the  vastator  attacks  this  plant,  it  lives, 
according  to  its  general  habit,  upon  the  under  surface  of 
the  leaf,  and  sucks  the  juices  in  the  usual  manner  ;  parts 
of  the  leaf  then  die  or  become  gangrenous  as  the  result : 
this,  however,  is  a  mere  local  mischief;  but  after  a  time, 
especially  subsequently  to  rain,  the  collar  of  the  plant 
becomes  affected,  and  the  entire  plant  dies  at  once. 

(327.)  The  mode  in  which  the  disease  manifests  itself 
in  this  vegetable  is  precisely  similar  to  that  in  the  pota- 
toe  plant  when  the  under-ground  stem  is  affected  ;  for  in 
this  case  the  upper  portion  of  the  root  rots,  while  the  root 
below  and  the  stems  above  are  sometimes  not  entirely 
destroyed ;  so  that  the  plant  is,  as  it  were,  cut  in  two  or 
decapitated. 

(328.)  The  appearance  of  the  gangrene  after  rain  is 
interesting,  for  it  shows  that  the  sap,  when  deprived  of  its 
solid  parts  by  this  animal,  will  no  longer  bear  the  addition 
of  water  ;  for  in  this  state  of  things  water  so  alters  the 
qualities  of  the  sap,  that  its  effect  upon  the  plant  is  posi- 
tively poisonous,  this  vital  fluid  thus  becoming  totally  unfit 
to  perform  the  functions  of  life. 

(329.)  The  carrot  is  a  useful  and  important  vegetable, 
which  we  employ  for  our  nourishment  as  well  as  for  the 
food  of  cattle.  It  however  is  attacked  by  the  vastator,  and 
rots  under  its  influence.  (Plate  vii.,  fig.  1.) 

(330.)  The  insect  lives  in  the  first  instance  upon  the 
larger  leaves,  which  it  destroys  locally  in  the  different 
parts  attacked.  After  a  time  the  central  portion  of  the  top 
of  the  carrot  begins  to  rot ;  this  rot  extends  downwards 

4* 


82  BEET,    SPINACH,    AND   CARROT   DISEASE. 

through  the  pith,  and  onwards,  till  at  last  the  leaves  are 
completely  separated  from  the  root,  as  in  the  case  of  the 
potatoe  and  turnip,  when  the  entire  plant  dies.  On  hand- 
ling a  plant  in  this  condition,  the  top  instantly  separates 
from  the  root. 

(331.)  I  believe  that  the  carrot  exhibits  the  effects  of 
the  disease  in  a  greater  degree  when  it  is  running  to  seed, 
as  in  that  case  it  seems  to  become  impatient  of  the  injury 
inflicted  by  the  insect. 

(332.)  The  injury  suffered  by  all  these  vegetables  cor- 
responds precisely  with  the  mischief  which  the  vastator 
works  upon  the  potatoe ;  it  is  in  fact  a  mere  transposi- 
tion of  the  damage  from  one  plant  to  another.  The  insect 
punctures  the  leaf,  sucks  its  juices,  injures  the  sap,  and 
causes  either  local  death  of  the  part  first  damaged,  or  the 
general  death  of  the  plant  by  inducing  gangrene  at  the 
collar. 


83 


CHAPTER  XIV. 

THE    APHIS    VASTATOR    ON    OTHER    PLANTS. 

Solarium  dulcamara  and  nigrum  attacked  by  the  vastator  (334). — 
Its  effect  upon  them  (335). — Greenhouse  and  other  species  of 
solanurn  (336). — Atropa  belladonna  (337).— Hyoscyamus  (338). 
—Tobacco  not  attacked  (339). — Stramonium  attacked  (340). — 
Comparative  effects  on  wild  and  cultivated  plants  (341). — Mode 
of  operation  (342). — Numerous  cruciferous  plants  attacked  (343, 
344).— Horse-radish  (345).— Tomato  (346).— Vastator  on  Indian 
corn  (347).— On  wheat  (348— 351).— Not  on  the  oat  (352).— 
Wild  barley  grass  (354). — Seedling  pasture  grass  (355). — Jerusa- 
lem artichoke  (357).— Nettle  (358)  —Mallow  (359).— Hearts- 
ease (360). — Coreopsis  tinctoria  and  'Balsam  (361). — Parsnip 
(362).— Chickweed  (363)  —Young  elders  (364).— Geranium  molle 
(365). — Plantain  (366). — Groundsel  (367). — Shepherd's  purse 
(368).— Spurge  (369).— Marigold  and  Thistles  (370).— Peach  and 
Nectarine  (371).— Celery  (372).— Probably  other  plants  also 
(373).— Remark  (374). 

(333.)  IT  became  a  matter  of  very  great  interest  to  as- 
certain whether  any  other  plants,  besides  the  potatoe  and 
the  turnip,  were  affected  by  the  vastator  ;  and  if  they  were, 
to  what  extent  they  were  likely  to  suffer.  To  the  investi- 
gation of  this  point,  then,  I  gave  my  undivided  attention, 
and  to  the  results  of  this  investigation  I  devote  the  present 
chapter. 

(334.)  I  have  found  the  insect  upon  the  Solatium  dulca- 
mara and  nigrum;  on  the  first  of  these,  when  it  grows 
about  the  hedges,  I  have  never  found  many  of  the  insects, 
for  they  do  not  appear  to  take  a  great  fancy  to  this  plant 
in  this  situation.  However,  upon  this  as  well  as  upon  the 
nigrum,  I  have  found  it  in  great  abundance  when  the  plant 


84      THE  APHIS  VASTATOR  ON  OTHER  PLANTS. 

was  growing  in  fields,  and  I  have  not  unfrequently  found 
every  leaf  so  densely  covered  with  this  pest  that  scarcely 
any  portion  of  the  leaf  was  visible  between  the  insects. 

(335.)  Their  effect  upon  the  nigrum  and  dulcamara, 
when  in  a  wild  and  natural  state,  is  to  destroy  each  leaf 
separately,  and  in  this  way  gradually  to  kill  the  plant. 
Upon  some  large,  luxuriant  specimens,  which  were  growing 
on  a  dunghill,  the  insect  was  very  abundant,  and  I  found  the 
roots  gangrenous  and  ulcerated  just  below  the  ground, 
showing  a  similar  character  to  that  evinced  by  the  potatoe. 

(336.)  Besides  these  solani,  I  have  found  it  upon  many 
greenhouse  and  other  species,  of  which  I  need  not  enume- 
rate the  names,  the  fact  being  of  importance  only  as  show- 
ing the  preference  evinced  by  this  aphis  for  this  genus  of 
plants. 

(337.)  The  Atropa  belladonna  is  in  like  manner  affect- 
ed; and  I  find  quantities  of  the  vastator  on  these  plants  in 
various  situations. 

(338.)  I  have  also  observed  the  vastator  on  a  species  of 
henbane,  growing  in  the  garden  of  Finsbury  Circus ;  and 
I  have  just  received  a  plant  of  the  hyoscyamus  from  Staf- 
ford, with  plenty  of  these  insects  feeding  on  it. 

(339.)  These  creatures  do  not  appear  to  me  to  like  the 
tobacco  plant,  for  after  examining  many  species  I  have 
failed  to  detect  a  single  insect,  either  in  its  winged  state,  or 
as  a  larva  or  pupa. 

(340.)  The  stramonium  is  attacked  by  this  creature, 
and  its  large  leaves  are  often  totally  destroyed  by  its  ra- 
vages. 

(341.)  In  all  these  instances,  the  effects  noticed  are  pre- 
cisely analogous  to  those  presented  by  the  potatoe,  but  in 
these  instances,  the  plants  resist  the  attacks  of  the  vastator 


THE    APHIS    VASTATOR    ON    OTHER     PLANTS.  85 

better,  being  in  a  more  uncultivated,  and  therefore  a  more 
natural  condition.  The  wild  potatoe  resists  the  invasion  to 
a  much  greater  extent  than  the  cultivated  varieties,  and 
these  solanaceous  plants  present  the  disease  in  precisely 
the  same  character  as  the  wild  potatoe. 

(342.)  In  some  cases,  a  small  portion  of  the  leaf  dies ; 
in  others,  the  effect  is  evidenced  on  a  greater  portion,  or  in 
the  whole  of  the  leaf.  The  larger  leaves  are  generally 
first  attacked  ;  and  when  the  plant  is  weakened,  the  insect 
migrates  to  the  smaller  leaves,  and  thus  successively  kills 
every  portion  of  the  plant :  it  then  takes  wing,  and  flies 
away  to  commit  its  ravages  elsewhere. 

(343.)  Next  to  plants  belonging  to  the  order  of  the  So- 
lanese,  those  included  in  the  order  Cruciferse  appear  to 
suffer  most.  Besides  the  turnip  and  the  Swede,  to  which 
I  have  given  a  distinct  chapter,  I  have  found  it  upon  the 
radish,  the  cabbage,  the  brocoli,  the  wild  turnip,  the  mus- 
tard, the  horse-radish,  and  other  cruciferous  plants. 

(344.)  The  cabbage  and  brocoli,  although  they  are  in- 
fected with  the  vastator,  are  generally  attacked  by  another 
Aphis  to  so  much  greater  an  extent,  that  the  vastator  is  but 
of  comparatively  little  consequence.  The  two  kinds  are 
frequently  to  be  met  with  upon  the  same  leaf,  committing 
their  ravages  in  company. 

(345.)  The  large  and  vigorous  leaf  of  the  horse-radish 
might  be  supposed  to  be  secure  from  injury  from  so  small 
and  seemingly  insignificant  an  animal  ;  yet  the  largest  of 
its  leaves  will  be  totally  destroyed  by  the  insect's  agency, 
and  the  plant  will  sho*w  a  tendency  to  rot  at  the  junction 
of  the  stem  with  the  root.  In  this  plant  the  disease  ap- 
pears in  its  early  stage  as  minute  points  of  discoloration, 
which  are  observable  at  the  places  where  the  creature 


86      THE  APHIS  VASTATOR  ON  OTHER  PLANTS. 

feeds,  and  which  enlarge  and  spread  until  ultimately  the 
entire  leaf  becomes  infected. 

(346.)  Upon  the  tomato,  which  has  also  been  affected 
with  a  disease,  I  discovered  winged  specimens  at  the  gar- 
dens of  the  Horticultural  Society,  but  was  not  successful 
in  finding  larvae  or  pupse,  perhaps  because  they  had  then 
all  assumed  their  final  state.  At  the  garden,  however,  of 
my  friend  Mr.  Terry,  at  Fulham,  I  found  the  insects  in 
all  stages  in  the  greatest  profusion. 

(347.)  The  Aphis  may  also  be  occasionally  found  upon 
the  Indian  corn.  I  had  it  sparingly  in  the  larva  state  upon 
some  of  the  plants  growing  in  my  garden  at  Finsbury 
Circus ;  and,  at  the  gardens  of  the  Horticultural  Society, 
I  discovered  it  in  the  winged '  state  upon  the  same  vegeta- 
ble in  great  abundance,  but  could  not  detect  any  larvae. 

(348.)  In  several  instances  I  have  found  the  creature 
upon  wheat  plants  which  were  growing  in  or  near  a  potatoe 
field ;  but  I  have  nevertheless  some  doubts  whether  it  can 
entirely  live  and  thrive  upon  it. 

(349.)  I  would  invite  particular  attention  to  this  ques- 
tion, for  it  will  be  a  very  serious  matter  if  the  insect  can 
live  and  propagate  freely  upon  this  grain.  In  examining 
this  subject,  the  naturalist  must  not  confound  another  large 
Aphis,  which  also  lives  upon  the  wheat,  with  the  vastator. 

(350.)  I  procured  two  or  three  plants  of  wheat  which 
had  sprouted  again  after  having  been  cut  down  with  the 
sickle,  and  upon  the  green  stalks  of  these  I  placed  speci- 
mens of  the  vastator,  which  there  lived  and  throve  very 
well,  and  propagated  their  species.  Since  writing  the 
above  paragraphs  I  have  had  even  further  evidence  of  this 
insect  preying  upon  the  wheat. 

(351.)  This  year  the  destroying  cloud  of  vastators  has 


THE    APHIS    VASTATOR   ON    OTHER    PLANTS.  87 

not  appeared  till  August.  Supposing,  however,  that  from 
their  excessive  numbers  it  should  come  before  the  grain  is 
formed,  there  is  no  doubt  that  the  creature  might  annihilate 
our  crop. 

(352.)  I  do  not  believe  that  this  creature  can  live  upon 
the  oat.  I  have  frequently  examined  oat  plants  in  the 
midst  of  dying  potatoes,  where  the  remnant  of  the  troop  of 
the  destroying  Aphides  were  glad  to  find  any  domicile,  but 
I  have  not  observed  a  single  plant  infected.  The  oat  is, 
however,  assailed  by  a  totally  different  Aphis,  which  is 
quite  as  partial  and  destructive  to  it  as  the  vastator  is  to 
the  potatoe. 

(353.)  I  have  placed  the  two  species  together  upon  an 
oat  plant  which  was  living  in  my  sitting-room.  In  a  few 
days  the  vastator  had  entirely  disappeared,  whilst  the  other 
species  throve  remarkably  well,  and  is  now  existing  in  all 
its  stages  of  development,  feeding  on  the  stalks  of  the 
young  grain. 

(354.)  Upon  the  wild  barley  grass,  however,  I  have 
found  the  vastator  in  great  abundance,  feeding  and  appa- 
rently thriving  well  upon  the  leaves,  which  very  soon  die, 
turn  yellow,  and  decay  under  its  destructive  influence. 
This  grass  is  also  preyed  upon  by  another  Aphis. 

(355.)  A  seedling  pasture  grass  is  liable  to  be  attacked 
by  the  vastator,  which  kills  leaf  after  leaf,  till,  in  some 
cases  which  I  have  seen,  the  whole  plant  is  totally  destroy- 
ed by  it.  In  this  case  the  vastator  is  generally  conjoined 
with  another  species,  which  is  hairy  and  has  no  abdominal 
tubercles. 

(356.)  I  am  not  aware  that  the  vastator  ever  lives  upon 
rye,  buck-wheat,  peas,  or  beans.  The  Aphis  which  attacks 


88      THE  APHIS  VASTATOR  ON  OTHER  PLANTS. 

the  pea,  though  equally  destructive,  is  a  very  distinct  in- 
sect from  the  vastator,  as  I  shall  hereafter  point  out. 

(357.)  I  have  found  the  vastator  somewhat  sparingly 
upon  the  Jerusalem  artichoke,  but  certainly  not  to  a  suffi- 
cient extent  to  do  mischief.  Some  artichokes  supplied  by 
a  London  greengrocer  for  the  dinner  table  were  hard  at 
one  end  and  soft  at  the  other ;  but  whether  this  has  been 
the  result  of  the  malady,  I  am  unable  to  state. 

(358.)  The  common  nettle  is  in  some  places  attacked 
by  the  vastator.  When  this  is  the  case,  the  leaves  die 
principally  at  the  edges  and  in  the  fleshy  parts,  in  a  man- 
ner precisely  similar  to  that  in  which  the  potatoe  suffers. 
At  last  the  whole  of  the  leaves  die,  and  the  plant  becomes 
ultimately  shrivelled.  The  root  is  found  to  be  soft  and 
watery,  and  shows  a  great  tendency  to  rot,  especially  at 
the  part  where  it  joins  the  stem.  The  nettle  is  also  attack- 
ed by  another  species  of  Aphis. 

(359.)  The  mallow,  also,  is  liable  to  the  attacks  of  this 
insect ;  and  when  attacked,  the  leaf  dies  much  in  the  same 
manner  as  is  seen  in  the  turnip ;  it  turns  yellow,  at  first 
partially  and  then  totally,  and  leaf  after  leaf  is  destroyed. 

(360.)  The  vastator  also  attacks  the  common  heartsease 
much  in  the  same  manner  as  in  the  last  instance  ;  and 
when  the  plant  has  been  attacked  for  a  certain  period,  the 
stem  generally  begins  to  rot  at  its  lower  part,  and  the  plant 
is  doubtless  eventually  destroyed. 

(361.)  The  Coreopsis  tinctoria  is  liable  to  the  attack  of 
the  vastator.  The  insect  lives  upon  the  leaves  and  des- 
troys  them  as  in  other  vegetables.  In  the  garden  balsam 
the  Aphis  injures  the  leaves  partially  or  totally,  and  thus 
destroys  its  existence,  and  in  this  case  the  root  swells  about 
the  collar. 


THE  APHIS  VASTATOR  ON  OTHER  PLANTS.      89 

(362.)  The  parsnip  is  infested  by  this  insect  sparingly. 
In  this  plant  the  leaves  die  from  its  attack,  and  lastly  the 
root  becomes  affected.  It  is  difficult  to  tell  the  precise  in- 
fluence the  vastator  has  upon  this  plant,  because  another 
Aphis  is  also  generally  found  conjoined  with  it.  (Plate 
vii.,  fig.  5.) 

(363.)  I  have  found  the  vastator  on  the  chickweed  plant 
in  some  instances,  but  not  as  yet  to  such  an  extent  as  to 
cause  extensive  damage. 

(364.)  I  have  seen  young  elder  trees  infested  with  this 
Aphis,  but  I  have  not  noticed  much  mischief  as  a  conse- 
quence. 

(365.)  The  Geranium  molle  has  its  leaves  and  stem, 
and  in  fact  the  whole  plant,  frequently  destroyed  by  this 
insect. 

(366.)  The  common  plantain  may  also  be  found  suffer- 
ing from  the  effects  of  the  ravages  of  the  vastator. 

(367.)  Of  all  plants  there  are  few,  or  perhaps  none, 
so  difficult  entirely  to  destroy  as  the  common  groundsel. 
Every  one  knows  that  its  eradication  from  the  garden  is 
scarcely  to  be  effected  ;  and  yet  this  little  insect  can  kill 
it  entirely  with  great  certainty.  It  will  attack  a  very 
vigorous  plant,  and  shortly  the  leaves  begin  to  change 
color  and  shrivel  up,  precisely  like  the  potatoe  ;  the  stem 
becomes  distended  with  water,  and  presently  dies.  I  could, 
in  one  particular  field,  have  procured  a  large  basket-full 
of  specimens  of  this  plant  utterly  destroyed  by  the  vastator. 

(368.)  The  shepherd's  purse  is  killed  in  almost  a  similar 
manner,  and  to  a  similar  extent,  although  a  very  hardy 
plant. 

(369.)  The  common  spurge  is  liable  to  be  most  exten- 


90       THE  APHIS  VASTATOR  ON  OTHER  PLANTS. 

sively  affected  by  the  vastator  ;  leaf  after  leaf  dies,  until 
the  plant  becomes  a  mere  withered  mass. 

(370.)  The  marigold  and  several  species  of  thistle  are 
also  attacked  by  the  vastator,  and  perish  in  the  usual  way. 

(371.)  The  peach  and  nectarine  leaves  are  infested  by 
this  parasite  :  it  generally  kills  the  leaves  partially. 

(372.)  The  celery  plant  is  commonly  attacked  to  a  small 
extent  by  the  vastator :  I  have  never  myself  seen  the 
insect,  however,  upon  this  plant  in  sufficient  quantity  to  do 
more  than  kill  a  leaf.  There  are  complaints  about  this 
esculent,  but  I  know  not  whether  the  injury  complained  of 
is  referable  to  this  cause.  The  plant  is  more  likely  to 
suffer  when  running  to  seed,  than  in  its  first  year's  growth. 

(373.)  Such  is  an  enumeration  of  the  plants  which  I 
have  found  to  be  affected  with  this  parasite.  And  there  is 
no  doubt  that  this  list  might  be  very  much  extended,  as  t 
myself  am  adding  to  the  number  every  day,  and  within 
the  last  two  or  three  days  I  have  even  discovered  it  abun- 
dantly on  the  Convolvulus  battata,  or  sweet  potatoe.  In 
this  examination  I  have  observed  that  cultivated  plants,  in 
which  particular  parts  of  the  plant  are  excessively  deve- 
loped or  hypertrophied,  are  more  prone  to  injury  than  the 
wild  plants  of  the  same  species.  In  the  wild  plants  the 
injury  generally  spreads  from  leaf  to  leaf,  whilst  in  the 
cultivated  varieties  it  appears  to  attack  root  and  leaf  at  the 
same  time. 

(374.)  The  above  list  shows  how  fearful  an  attachment 
this  insect  has  to  plants  which  are  serviceable  to  man  for 
food,  as  well  as  for  medicine,  well  entitling  it  to  the  name 
which  I  have  given  it — the  vastator,  or  "  destroyer." 


91 


CHAPTER  XV. 

INJURIES    SIMILAR   TO    THOSE    CAUSED    BY    THE    VASTATOR, 
PRODUCED    BY    OTHER    APHIDES. 

Aphides,  numerous  species  of  (375).— Aphis  of  the  hop  (376). — 
Aphis  of  the  cabbage  and  turnip  (377). — Aphis  of  the  pea  (378). 
—Instance  of  mischief  by  [Kirby]  (379). — Bean  aphis  (380). — 
Apple-tree  aphis  (381).— Sugar-cane  (382).— Aphis  of  larch 
(383). — Rose-tree  aphis  (384). — Aphis  on  couch-grass  (385). — 
Aphides  generally  (386).' 

(375.)  THE  species  comprised  in  the  family  "  Aphides" 
are  a  sad  pest  to  the  human  race.  It  is  quite  uncertain 
how  many  there  are,*  for  abstract  science  is  so  little  ap- 
preciated, so  little  cared  for  or  encouraged,  that  few  can 
afford  to  spend  their  time  in  watching  an  Aphis ;  and  thus, 
when  great  calamities  come,  men  see  not  the  cause,  because 
they  know  not  the  insect. 

(376.)  The  Aphis  of  the  hop  lives  upon  the  leaves  of 
that  plant,  and  does  so  much  damage,  that  in  bad  years  its 
ravages  will  cause  a  reduction  in  the  value  of  hops  pro- 
duced in  Great  Britain  amounting  to  very  near  3,000,0007. 
sterling.  This  year  the  insects  threatened  to  destroy  the 
crop,  but  suddenly  a  thunder  storm  swept  every  one  of 
them  from  the  face  of  the  plantations,  and  so  thoroughly 
were  they  annihilated,  that  when  I  sent  to  Kent  to  procure 
some  specimens  of  this  species,  I  received  answer  that 
there  were  none  to  be  found. 

*  Stephens,  in  his  "  Systematic  Catalogue  of  British  Insects,"  has 
recorded  forty-nine  named  species  of  the  genus  Aphis  alone,  and 
others  appertaining  to  the  several  cognate  genera. 


92  INJURIES   PRODUCED    BY   OTHER   APHIDES. 

(377.)  The  Aphis  of  the  cabbage  and  turnip  is  very  de- 
structive to  those  plants  ;  it  is  distinguished  from  the  vas- 
tator  by  its  white  color,  its  short  abdominal  tubercles,  and 
the  structure  of  its  antennse.  It  is  not  nearly  so  active  as 
the  vastator,  and  remains  for  a  long  period  in  one  place. 
It,  however,  destroys  the  leaf,  and  produces  a  similarly 
injurious  effect  upon  the  plant. 

(378.)  The  Aphis  of  the  pea  is  a  very  destructive 
species,  and  frequently  causes  our  late  crops  of  peas  to  rot 
entirely  off.  It  is  a  noble-looking  fellow,  and  about  twice 
as  large  as  the  vastator.  Its  color  is  green,  and  it  lives 
upon  the  leaves  in  the  usual  way  ;  the  mode  in  which  it 
acts  upon  the  pea  being  exactly^similar  to  that  in  which 
the  vastator  affects  other  plants.  The  leaf  is  injured,  the 
vigor  of  the  plant  is  diminished ;  and  the  plant  perishes 
either  at  the  leaf,  stem,  or  at  the  junction  of  the  stem  with 
the  root ;  when  the  connection  between  the  root  and  leaf 
being  lost,  the  plant  necessarily  dies. 

(379.)  Kirby  mentions  that  in  1810  the  produce  of  the 
pea  crops  did  not  amount  to  much  more  than  the  seed 
sown,  and  that  many  farmers  turned  their  swine  into  their 
pea-fields,  not  thinking  the  crop  worth  harvesting. 

(380.)  The  bean  also  has  its  Aphis,  which  frequently 
causes  an  almost  total  failure  of  the  crop.  The  bean  leaf 
is  injured,  the  stalks  grow  black,  and  the  plant  perishes, 
producing  very  little  or  no  fruit.  The  gardeners  generally 
conquer  this  animal  by  cutting  off  the  tops  of  the  plants 
with  a  sickle. 

(381.)  A  small  Aphis*  attacks  the  apple-tree  :  it  is  called 

*  We  here  use  the  general  term  "  Aphis,"  because  the  insect  be- 
longs to  the  family  Aphides ;  it  does  not,  however,  strictly  speaking, 
belong  to  the  genus  Aphis,  but  to  the  cognate  genus  Eriosoma,  one 


INJURIES   PRODUCED    BY    OTHER   APHIDES.  93 

the  Aphis  Lanigera,  and  has  a  woolly  body,  and  when 
crushed  it  is  of  so  bright  a  red  as  to  stain  things  with 
which  it  comes  in  contact.  This  Aphis  lives  upon  the 
bark  and  roots;  it  is  very  destructive,  and  will  kill  even 
the  largest  trees  in  an  orchard.  Around  the  metropolis  it 
destroyed  thousands  of  trees ;  and  when  it  spread  into 
Gloucestershire,  it  almost  caused  the  abandonment  of  the 
manufacture  of  cider.  It  began  in  a  nursery  in  Sloane 
street,  and  spread  over  England,  committing  its  ravages 
for  a  number  of  years.  Sir  Joseph  Banks  relates  that  it 
destroyed  so  many  codlin  trees  in  one  garden,  the  rental 
of  which  was  50Z.  a  year,  as  to  almost  annihilate  the  pro- 
duce. This  insect  has  lately  been  rather  scarce,  and 
though  it  still  exists,  yet  it  does  but  little  damage  at  the 
present  time. 

(382.)  The  leaves  of  the  sycamore,  in  some  places, 
present  a  most  remarkable  maculated  appearance,  from 
large  black  spots  as  big  as  a  sixpence.  These  are  owing 
to  a  fungus  which  follows  the  attack  of  a  noble  Aphis, 
which  honors  this  tree  by  sucking  its  vital  fluid.  In  this 
instance  we  have  a  case  of  local  death  from  the  puncture 
of  the  Aphis. 

The  sugar-cane,  according  to  Kirby,  has  its  Aphis, 
which  sometimes  destroys  the  whole  crop. 

(383.)  Kirby  also  states  that  the  larch,  in  particular,  is 
inhabited  by  an  Aphis,  which  exudes  a  waxy  substance, 
like  filaments  of  cotton,  and  becomes  so  infinitely  multi- 
plied as  to  whiten  the  whole  tree,  which  often  perishes  in 
consequence  of  the  attack. 

of  the  distinguishing  characters  of  which  group  is  well  indicated  by 
the  generic  name,  which  is  made  up  of  the  words  Epiof  wool,  and 
o-w/ja  a  body. 


94  INJURIES    PRODUCED    BY    OTHER    APHIDES. 

(384.)  The  rose-tree  is  commonly  infested  by  an  Aphis 
which  feeds  upon  the  tops  of  the  shoots  and  the  adjacent 
leaves ;  and  I  have  been  informed  by  Dr.  Fergus  that 
several  trees  have  this  year  had  nearly  all  their  branches 
destroyed  by  its  ravages.  This  Aphis  seems  to  have  a 
special  aversion  to  cold  water  ;  a  good  syringing  with 
which  generally  compels  them  all  to  relax  their  mis- 
chievous hold,  and  a  second  application  commonly  washes 
the  whole  tribe  to  perdition. 

(385.)  If  there  is  one  plant  more  than  another  remark- 
able  for  its  power  of  resisting  destroying  agencies,  it  is, 
perhaps,  the  couch-grass ;  but  I  have  observed  that  even 
this  weed  has  its  leaves  attacked  by  a  beautifully  spotted 
Aphis,  which  gradually  destroys  them  and  kills  the  whole 
plant. 

(386.)  The  family  of  Aphides  is  most  numerous,  and 
doubtless  all  the  species  act  in  an  equally  injurious  man- 
ner. It  is  not,  however,  the  purport  of  this  work  to  give 
a  history  of  the  Aphis,  and  I  quote  these  few  instances 
merely  to  show  that  the  vastator  is  not  singular  in  injuring 
man  by  its  attacks  upon  various  plants. 


CHAPTER  XVI. 

ON    THE    EXCESSIVE    APPEARANCE     OF     PARTICULAR    INSECTS. 

Natural  balance  in  the  relative  numbers  of  living  creatures  (357). — 
This  balance  occasionally  disturbed  (388). — Excessive  appear- 
ance of  Aphis  vastator  (389).— Instance  at  Brighton  (390).— 
Insect  plagues  recorded  in  the  Old  Testament  (391). — Kirby  and 
Spence  (392).— Ravages  of  the  May-beetle  (393,  394).— Ravages 
of  several  species  of  insects  (395,  396).— Bostrichus  typographus 
(397).— Locust  plagues  (398,  399).— Wasps  (401).— Honeydew 
(402).— Controlling  agents  (404).— The  exaggerated  increase  of 
particular  insects  not  continuous  (405). 

(387.)  WE  have  now  found  that  the  gangrene  of  the 
potatoe  is  to  be  attributed  to  an  excessive  increase  of  the 
Aphis  vaslator.  As  a  general  rule,  Nature  has  exquisitely 
contrived  that  every  organic  body  should  bear  certain 
relations  to  other  organic  bodies,  and  hence  the  earth 
remains  tenanted  with  a  great  variety  of  beings,  and  none 
are  in  excess  to  the  detriment  of  the  rest. 

(388.)  In  particular  instances,  however,  this  balance 
of  tenantry  is  disturbed,  and  occasionally  some  one  insect 
becomes  too  redundant,  and  occupies  more  than  its  allotted 
space. 

(389.)  The  excessive  appearance  of  the  Aphis  vastator 
is  an  instance  of  this  character ;  for  to  such  an  extent  has 
it  been  recently  found,  that  in  a  field  of  beet,  less  than  a 
quarter  of  an  acre  in  extent,  there  were  countless  millions 
of  this  parasite.  It  appears  that  some  time  previous  to  a 
thunder-storm  this  Aphis  is  apt  to  fly  ;  and  on  September 


9b  ON    THE    EXCESSIVE    APPEARANCE     OF    INSECTS. 

9th  I  observed  at  Clapton  a  reddish  cloud  exterior  to  a 
thunder-cloud,  and  this  was  composed  of  myriads  of  the 
winged  insects,  which  kept  dropping  here  and  there  in 
such  profusion,  that  by  waving  the  hat  numbers  might 
soon  have  been  caught.  On  examining  the  spiders'  webs 
many  were  to  be  found  adhering  in  each  web.  From  this 
it  is  apparent  that  the  excess  of  the  vastator  is  analogous 
to  other  excesses  heretofore  known. 

(390.)  I  am  informed  by  Mr.  Kennedy,  that  on  the  14th 
of  September,  in  this  year,  a  cloud  of  Aphides  passed 
over  the  Downs  at  Brighton,  and  such  were  their  numbers 
that  he  became  literally  covered  with  them,  and  was  very 
glad  to  turn  his  back  to  avoid  their  settling  upon  his  face. 
Mr.  W.  R.  Smee  states,  that  he  was  informed  by  the  in- 
habitants of  Freshwater,  Isle  of  Wight,  that  they  had 
observed  this  year  vast  clouds  of  insects,  or  flies,  appear- 
ing like  a  great  mist,  and  they  occupied  five  or  six  hours 
in  their  passage.  Mr.  W.  R.  Smee  also  states  that  he 
was  informed  by  a  farmer  at  Chichester  that  he  saw  insects 
settle  in  large  numbers  upon  his  potatoes.  It  is  impossible 
to  tell  now  what  these  troops  of  insects  were,  for  neither 
Mr.  Kennedy  nor  my  brother  can  state  with  certainty. 
The  former  gentleman  stated  that  they  resembled  a  winged 
Aphis  vastator,  which  I  showed  him. 

(391.)  The  earliest  account  of  an  excessive  increase  of 
particular  insects  is  to  be  found  in  the  8th  chapter  of 
Exodus,  where  it  is  recorded  that  the  Egyptians  were 
plagued  with  an  immense  multiplication  of  lice.  We  find 
also,  in  the  same  chapter,  that  the  land  was  corrupted  by 
reason  of  the  swarm  of  flies.  In  the  book  of  Joel  is  con- 
tained a  beautiful  and  highly  poetical  description  of  the 
effect  of  this  excessive  increase  of  insects  :  "  For  a  nation 


; 

ON    THE    EXCESSIVE    APPEARANCE    OF    INSECTS.  97 

has  come  up  upon  my  land,  strong  and  without  number;" 
and  "  the  field  is  wasted,  the  land  mourneth  ;  for  the  corn 
is  wasted,  the  new  wine  is  dried  up,  and  the  oil  languish- 
eth."  In  the  2d  chapter  of  the  same  book,  verse  1  to  11, 
we  meet  with  the  most  appalling  description  of  another 
insect  plague,  where  the  insects  are  spoken  of  as  "  the 
army  of  the  Almighty,  strong  to  execute  his  word."  In 
the  10th  chapter  of  Exodus  we  find  it  recorded  that  a 
numerous  swarm  of  locusts  "  covered  the  face  of  the 
whole  earth,  so  that  the  land  was  darkened ;  and  tlfty  did 
eat  every  herb  of  the  land,  and  all  the  fruit  of  the  trees 
which  the  hail  had  left." 

(392.)  If  we  turn  to  the  charming  work  of  Kirby  and 
Spence,  we  shall  find  many  instances  of  this  excessive 
increase  of  various  insects,  showing  that  the  present  mul- 
titudinous appearance  of  the  vastator  is  perfectly  analogous 
with  instances  heretofore  known. 

(393.)  In  1785  many  provinces  of  France  were  so 
ravaged  by  the  larva  or  grub  of  the  cockchafer,  that  a 
premium  was  offered  for  the  best  means  of  destroying 
them  :  and  some  time  ago  eighty  bushels  of  the  beetle 
were  collected  by  a  farmer  near  Norwich.  I  remember 
also  this  pest  visiting  the  Circus  some  years  ago,  and 
threatening  to  destroy  every  plant  and  every  blade  of  grass 
there  existing. 

(39'.)  In  1688  the  cockchafers  themselves  filled  the 
hedges  and  trees  in  part  of  the  county  of  Galway  in  such 
infinite  numbers,  that  they  were  seen  clinging  to  each 
other  in  clusters,  like  bees  when  they  swarm.  When  on 
the  wing  they  darkened  the  air,  and  produced  a  sound  like 
that  of  distant  drums.  When  they  were  feeding,  the 
noise  of  their  jaws  might  be  mistaken  for  the  sawing  of 

5 


98  ON    THE    EXCESSIVE    APPEARANCE    OF    INSECTS. 

timber  ;  and  in  a  short  time  the  leaves  of  all  the  trees  for 
many  miles  round  were  so  totally  destroyed  by  them,  that 
at  midsummer  the  country  wore  the  aspect  of  the  depth 
of  winter. 

(395.)  In  1788  and  1794  two-thirds  of  the  crop  of  cotton 
in  Crooked  Island,  one  of  the  Bahamas,  was  destroyed  by 
a  lepidopterous  larva. 

In  1734  and  1735  vast  swarms  of  a  beetle  devoured  al- 
most every  vegetable  production  of  the  island  of  Barbadoes, 
particularly  the  potatoe. 

In  1786  the  turnip  crops  in  Devonshire  were  destroyed, 
to  the  value  of  100,0007.,  by  the  turnip  flea. 

In  1735  the  Plusia  gamma,  which  is  a  pretty  common 
moth  with  us,  increased  to  such  an  extent  in  France  as  to 
infest  the  whole  country.  Vast  numbers  of  the  larvse  tra- 
velled from  field  to  field,  and  in  gardens  devoured  every- 
thing, leaving  only  the  stalks  and  veins  of  the  leaves. 

(396.)  In  1731  the  oaks  in  France  were  terribly  devas- 
tated by  an  excessive  increase  of  Hypogymna  dispar  (the 
gipsy  moth) ;  and  in  1797  many  of  the  pine  forests  about 
Bayreuth  suffered  a  similar  injury. 

In  1782  the  brown-tail  moth  caused  great  alarm  to  the 
inhabitants  of  the  vicinity  of  the  metropolis,  when  rewards 
were  offered  for  collecting  the  caterpillars  ;  and  the  church- 
wardens and  overseers  of  the  parishes  attended  to  see  them 
burnt  by  bushels. 

(397.)  There  is  a  small  beetle,  the  Bostriclius  iypogra- 
phus,  which  bores  into  the  fir.  This  insect  was  particu- 
larly prevalent  about  the  year  1665 :  it  reappeared .  in 
1757,  redoubled  its  injuries  in  1769,  and  arrived  at  its 
height  in  1783,  when  the  number  of  trees  destroyed  by  it 
in  the  above  forest  alone  was  calculated  at  a  million  and  a 


ON    THE    EXCESSIVE    APPEARANCE    OF    INSECTS.  99 

half,  and  the  inhabitants  were  threatened  with  a  total  sus- 
pension of  the  working  of  their  mines,  and  with  consequent 
ruin. 

(398.)  One  of  the  greatest  occasional  pests  in  the  form 
of  an  insect  is  the  locust.  Orosius  stated,  that,  in  the  year 
of  the  world  3800,  Africa  was  infested  with  such  infinite 
myriads  of  these  animals,  that,  having  devoured  every 
green  thing,  and  afterwards  flown  off  to  sea,  they  were 
drowned ;  and  being  cast  up  on  the  shore  by  the  tide,  they 
rotted,  and  emitted  a  stench  greater  than  could  have  been 
produced  by  the  carcases  of  100,000  men.  St.  Augustine 
also  mentions  a  plague  "  to  have  arisen  in  that  country 
from  the  same  cause,  which  destroyed  no  less  than  800,000 
persons  in  the  kingdom  of  Masinissa  alone,  and  many  more 
in  the  territories  bordering  upon  the  sea. 

(399.)  In  one  year  a  million  of  men  perished  from  the 
stench  of  the  carcases  of  the  insects ;  in  another  30,000 
died  of  starvation ;  and  Barrow  mentions  that  in  1784  an 
area  of  nearly  2000  miles  was  covered  by  them. 

In  1778  and  1780  the  empire  of  Morocco  was  so  infested, 
that  vast  numbers  of  the  inhabitants  perished,  and  the  roads 
and  streets  exhibited  the  unburied  carcases  of  the  dead. 

(400.)  These  instances  I  have  selected  from  the  truly 
delightful  work  of  Kirby  and  Spence  ;  but  I  might  mention 
many  more  instances  from  my  own  recollection.  I  have, 
however,  given  enough  to  show  that  the  relation  of  particu- 
lar insects  to  other  parts  of  creation  is  sometimes  disturbed, 
and  that  any  species  may  appear  in  this  exaggerated  man- 
ner. 

(401.)  Our  naturalist  Gilbert  White  states  that  «  in  1783 
there  were  myriads  of  wasps,  which  would  have  devoured 
all  the  produce  of  my  garden,  had  we  not  set  the  boys  to 


100         ON    THE    EXCESSIVE    APPEARANCE    OF    INSECTS. 

take  the  nests,  and  caught  thousands  with  hazel  twigs 
tipped  with  bird-lime ;  we  have  since  employed  the  boys 
to  take  and  destroy  the  large  breeding  wasps  in  the 
spring." 

(402.)  "  In  the  sultry  season  of  1783,  honey-dews  were 
so  frequent  as  to  deface  and  destroy  the  beauties  of  my 
garden.  My  honeysuckles,  which  were  one  week  the 
most  sweet  and  lovely  objects  that  eye  could  behold,  be- 
came the  next  the  most  loathsome,  being  enveloped  in  a 
viscous  substance,  and  loaded  with  black  Aphides  or 
smother  flies." 

(403.)  "  On  the  1st  of  August,  about  half  an  hour  after 
three  in  the  afternoon,  the  people  of  Selborne  were  surprised 
by  a  shower  of  Aphides,  which  fell  in  these  parts.  They 
who  were  walking  the  streets  at  that  time  found  themselves 
covered  with  these  insects,  which  settled  also  on  the  trees 
and  gardens,  and  blackened  all  the  vegetables  where  they 
alighted.  These  armies,  no  doubt,  were  then  in  a  state  of 
emigration  and  shifting  their  quarters,  and  might  perhaps 
come  from  the  great  hop  plantations  in  Kent  or  Sussex,  the 
wind  being  that  day  north.  They  were  observed  at  the 
same  time  at  Farnham,  and  all  along  the  vale  at  Alton." 

(404.)  Whilst  recently  on  a  short  visit  to  Northaw  Park, 
my  attention  was  directed  to  the  destruction  which  had  this 
year  taken  place  amongst  the  firs ;  and  most  elegant  trees, 
of  fifty  years'  growth,  upon  the  lawn,  were  so  much  da- 
maged, as  to  render  it  doubtful  whether  they  would  ever 
recover.  I  am  informed  also  that  in  some  places  hundreds 
of  these  trees  have  been  totally  killed  this  year  by  the 
ravages  of  the  insect,  but  I  am  uncertain  as  to  the  exact 
creature  which  has  caused  the  injury. 

Locusts  are  also  said  to  have  appeared  in  the  east  this 


RELATION  OF  VASTATOR  TO  OTHER  APHIDES.    10 1 

year,  and  I  know  that  many  rare  insects,  as  the  Camber, 
well  beauty,  the  death's  head  moth,  and  the  unicorn  hawk 
moth,  have  been  taken  this  year  more  abundantly  than 
usual. 

(405.)  Insects  are  kept  in  bounds  by  atmospheric  causes, 
birds,  bats,  reptiles,  and  very  mariy  species  of  insects  which 
prey  upon  others.  Therefore,  when  one  insect  shows  it- 
self in  too  great  abundance,  we  must  look  out  for  the  par- 
ticular destroyer  destined  by  nature  to  keep  it  within  its 
accustomed  limits. 

The  human  species  has  frequently  been  threatened  with 
total  destruction  by  the  locust,  and  yet  man  still  lives,  and 
the  locust  has  returned  to  its  proper  limits  in  the  circle  of 
creation. 

The  last  two  or  three  years  the  vastator  has  threatened 
millions  of  men  ;  but,  doubtless,  at  last  the  harmony  of  the 
universe  will  be  restored,  the  super-abundance  of  the  in- 
sects will  be  checked  and  controlled,  and  man  will  be  saved 
from  its  attacks. 


CHAPTER  XVII. 

RELATION     OF     THE    VASTATOR     TO     OTHER   APHIDES    AND    TO 
FUNGI. 

Analogy  between  the  different  aphides  (406— 409).— Probable  effect 
of  the  predominance  of  one  species  (410). — Destructive  power  of 
aphis  (411).— Relation  of  fungi  to  aphides  (412). 

(406.)  THE  numerous  species  of  Aphis  bear  a  strong 


102    RELATION  OF  VASTATOR  TO  OTHER  APHIDES. 

analogy  with  each  other;  they  all  live  upon  the  juices  of 
plants,  and  are  the  prey  of  certain  parasitic  Hymenopiera 
which  are  smaller  than  themselves. 

(407.)  I  have  generally  observed,  when  I  have  found 
any  one  species  of  Aphis  in  any  particular  spot,  that  other 
kinds  wer,e  to  be  met  with  in  profusion  in  the  neighbor- 
hood :  hence,  it  is  not  at  all  uncommon  to  find  many  kinds 
of  Aphis  in  the  same  field,  not  feeding  upon  the  same 
plant,  but  each  upon  its  own  proper  food. 

(408.)  This,  however,  is  not  by  any  means  an  univer- 
sal rule,  for,  although  the  vastator,  the  brassicse,  and  vari- 
ous other  kinds  have  been  in  great  abundance  this  season, 
yet  the  hop  Aphis  disappeared  on  the  commencement  of  a 
thunder-storm. 

(409.)  The  brassicse  is  so  abundant  this  year  that  some 
of  the  greens  supplied  in  London  are  covered  with  count- 
less myriads  of  them,  and  hence  we  may  infer,  that  this 
year  it  is  not  the  balance  of  Aphides  only  which  is  de- 
stroyed, but  the  balance  between  the  Aphides  and  their 
parasites. 

(410.)  From  this  view  of  the  question,  even  more  im- 
portance must  be  attached  to  the  preternatural  appearance 
of  the  Aphis;  for,  as  perhaps  every  plant  has  some  para- 
sitical Aphis  which  damages  its  juices,  it  follows  that  the 
excess  of  one  kind  may  ultimately  injure  all  vegetable 
bodies. 

(411.)  This,  indeed,  gives  us  a  fearful  idea  of  the  de- 
structive character  of  the  Aphis,  and  shows  us  that  if  one 
species  is  in  excess,  all  vegetables  may  suffer. 

(412.)  There  appears  to  me  to  be  a  very  close  relation 
between  the  injury  committed  by  the  Aphides  and  the  ap- 
pearance of  fungi ;  for  in  numerous  cases  where  I  have 


PI,  10. 


Stone  ty  £fr-a.t$ca,p. 


DESTROYERS  OF  APHIDES.  103 

observed  fungi  on  the  leaf,  I  have  also  noticed  Aphides  on 
the  plant. 

It  is  also  a  singular  fact,  that  there  is  a  word  in  the  He- 
brew language  which  means  blight  and  mildew,  collec- 
tively, meaning  thereby  Aphis  and  fungus. 

The  Aphis,  however,  only  favors  the  growth  of  the  fun- 
gus by  injuring  the  vital  powers  of  the  plant;  and,  there- 
fore, any  other  circumstance  which  can  debilitate  the  plant 
doubtless  may  favor  the  appearance  of  the  fungus. 


CHAPTER  XVIII. 

NATURAL     REMEDIES     FOR     THE     PRESENT     DISEASE     AMONG 
PLANTS. 

Animals  destructive  to  aphides  (413). — Coccinella  (414,  415) ; — 
Profusion  of  (416).— The  Gauze-wing  (418).— Larvee  of  Sylphidae 
(419).— Parasitic  Hymenoptera  (420,  421). — Other  Hymenoptera 
(422).— Earwing  and  species  of  Acarus  (424). — Spiders  (425).— 
The  soft-billed  birds  (426,  427).— Ducklings  (428). 

(413.)  THE  balance  of  creation  is  disturbed, — the  Aphis 
vastator  has  increased  to  an  alarming  extent, — we  must 
therefore  inquire  by  what  means  this  creature  is  generally 
kept  within  due  bounds,  and  we  shall  find  that  numerous 
animals  prey  upon  it. 

(414.)  The  lady-bird  or  lady-cow  (Coccinella),  together 
with  its  larva,  makes  great  havoc  amongst  the  Aphides ; 
and  thousands  of  these  creatures  are  to  be  found  upon  the 
potatoe,  the  turnip,  and  other  vegetables,  when  the  vastator 


104  DESTROYERS    OF    APHIDES. 

is  there.  You  will  sometimes  even  be  guided  to  the  Aphis 
by  the  presence  of  the  lady-bird. 

(415.)  Kirby  and  Spence  say  "  that  in  France  they  re- 
gard these  CoccinellfB  as  sacred  to  the  Virgin  ;  and  call 
them  *  Vaches  a  Dieu,  Betes  de  la  Vierge  ;'  "  and  even  in 
this  country  they  are  great  favorites  with  children. 

(416.)  "  In  1307  the  shore  at  Brighton  and  all  the  water- 
ing-places  on  the  south  coast  was  literally  covered  with 
them,  to  the  great  surprise  and  even  alarm  of  the  inhabit- 
ants, who  were  ignorant  that  they  were  emigrants."  I 
have  heard  also  that  at  Ramsgate  the  entire  cliff  has  been 
occasionally  completely  covered  with  this  pretty  little 
beetle. 

(417.)  There  is  no  doubt  that  if  we  could  breed  these 
creatures  by  millions,  we  could  annihilate  the  Aphis ;  but 
the  vastator  is  such  a  sad  rover,  that  I  suspect  it  often  es- 
capes the  beetle.  The  larva  of  the  beetle  is  more  destruc- 
tive to  these  insects  than  the  beetle  itself.  (Plate  x.,  figs. 
10,  11,  12.) 

(418.)  Kirby  and  Spence  state  that  "  there  is  a  beauti- 
ful genus  of  four-winged  flies,  whose  wings  resemble  the 
finest  lace,  and  whose  eyes  are  often  as  brilliant  as  bur- 
nished rnetal,  the  larvee  of  which,  Reaumur,  from  their  be- 
ing insatiable  devourers  of  Aphides,  has  named  the  lions 
of  the  Aphides.  When  amongst  the  Aphides,  like  wolves 
in  a  sheep-fold,  they  make  dreadful  havoc;  half  a  minute 
suffices  one  of  them  to  suck  the  largest  Aphis :  and  the 
individual  of  one  species  clothes  itself,  like  Hercules,  with 
the  spoils  of  the. hapless  victims."  (Plate  x.,  figs.  5,  6, 
Chrysopa  perla). 

(419.)  There  are  many  species  of  Sylpliida  (a  family 
of  dipterous  insects),  which  destroy  Aphides.  The  larvae 


DESTROYERS  OF  APHIDES.  105 

of  these  creatures  are  armed  with  a  singular  mandible, 
furnished,  like  a  trident,  with  three  points,  with  which 
they  transfix  their  prey.  They  lie  at  their  ease  under  a 
leaf  or  upon  a  leaf,  surrounded  by  such  hosts  of  Aphides, 
that  they  can  devour  hundreds  without  changing  their  sit- 
uation. (Plate  x.,  figs.  7,  8,  9,  Scava  pyrastri.) 

(420.)  Various  hymenopterous  insects  are  great  des- 
troyers of  Aphides.  There  are  some  genera  which  deposit 
their  eggs  in  the  bodies  of  the  Aphis  ;  the  egg  grows  and 
becomes  a  maggot,  which  eats  up  the  creature,  avoiding, 
however,  the  vital  parts  till  the  last.  The  Aphis  when 
attacked  by  this  parasite  swells  up,  assumes  a  globular 
form,  and  at  length  dies  and  remains  adherent  to  the  leaf. 
Aphides  in  this  state  are  to  be  found  on  every  plant,  and, 
indeed,  upon  almost  every  leaf  which  is  affected  with  the 
insect.  In  a  few  days  after  the  death  of  the  Aphis,  the 
inclosed  creature  eats  a  little  circular  hole  and  comes  forth 
a  winged  insect.  The  insects  which  thus  destroy  the 
Aphides  by  thousands  are  called  Ichneumons,  but  how 
many  species  there  may  be  which  actually  attack  the 
Aphis  I  am  ignorant.  I  have  figured  two  which  have 
escaped  from  Aphides  in  my  own  possession.  (Plate  x., 
figs.  3,  4.) 

(421.)  These  insects  are  very  minute,  and  may  be 
known  at  once  from  the  winged  Aphides  by  the  total  want 
of  resemblance  in  every  particular. 

Curiously  enough  these  creatures  again  have  their 
parasites ;  for  other  Hymenoptera,  the  ChalcididcB  for 
instance,  deposit  their  eggs  in  the  maggot  of  the  already 
punctured  Aphis ;  and  thus  we  have  an  Aphis  with  a 
maggot  within  its  body  eating  it  up ;  and  lastly,  a  maggot 
within  this  maggot  devouring  that  also.  I  have  figured  an 


106  DESTROYERS  OF  APHIDES. 

example  of  this  parasite  upon  parasite.     (Plate  x.,  fig.  14, 
Colax  dispar.) 

In  part  verification  of  the  lines  : — 

"  Great  fleas  and  little  fleas  have  smaller  fleas  to  bite  'em, 
The  smaller  fleas  have  lesser  fleas,  so  on  ad  infinitum." 

Quoted  in  Stephens'  Illustrations,  vol.  vii. 

(422.)  There  is  another  set  of  hymenopterous  insects, 
which  seize  upon  Aphides  and  carry  them  off  to  their 
habitation  to  feed  their  own  children.  It  is  said  that  thou- 
sands are  thus  killed.  Examples  of  this  order,  which  per- 
form this  friendly  office  to  man,  are  to  be  found  in  the 
genera  of  Psen,  Diodontis,  Pemphredon,  and  Tropoxylon. 
(Plate  x.,  figs.  1,  2,  13,  15.) 

(423.)  I  have  no  doubt  that  the  omnivorous  and  greedy 
wasp  would  have  no  objection  to  eat  Aphides,  if  he  could 
get  nothing  better.  I  formerly  tried  to  press  two  or  three 
colonies  of  wasps  into  my  service,  to  make  skeletons  of 
small  animals,  but  their  voraciousness  was  so  great,  that 
they  not  only  ate  the  flesh  but  the  bones  also. 

(424.)  I  very  much  suspect  that  the  earwing  is  a  great 
devourer  of  Aphides,  although  it  is  stated  that  it  is  entirely 
a  vegetable  feeder.  When  I  have  gone  at  night  with  a 
lantern  to  see  what  the  Aphides  were  about,  I  have  fre- 
quently observed  numbers  of  earwings  very  busy  at  the 
places  where  the  Aphides  greatly  abounded,  but  I  have  not 
actually  seen  them  devour  them.  There  is  a  very  beauti- 
ful Acarus  which  is  always  to  be  found  in  company  with 
the  Aphides.  He  seizes  the  Aphis,  and  appears  to  suck  its 
juices.  (Plate  v.,  fig.  9.) 

(425.)  Numbers  of  black   and  other  spiders  doubtless 


DESTROYERS    OF    APHIDES.  107 

prey  upon  Aphides,  but  I  have  frequently  observed  when 
the  winged  Aphis  is  caught  in  the  spider's  web,  that  the 
spider  has  not  attacked  it.  Whether  this  arises  from  his 
having  been  surfeited  with  the  great  superfluity  of  this 
kind  of  food  this  year,  or  whether  he  does  not  like  the 
flavor  of  them,  I  am  at  a  loss  to  determine. 

(426.)  Doubtless  Aphides  form  dainty  food  to  the  soft- 
billed  birds,  and  if  they  would  entirely  live  upon  them, 
they  would  doubtless  devour  three  or  four  thousand  at  a 
single  meal.  With  regard  to  birds,  however,  a  very  impor- 
tant question  is  opened  for  our  consideration ;  for  if  they 
prefer  the  parasites  of  the  Aphis  to  the  Aphides  themselves, 
then  their  presence  would  be  hurtful ;  if,  on  the  contrary, 
they  eat  the  Aphides  and  avoid  the  parasites,  then  they 
would  act  most  beneficially. 

(427.)  When  a  schoolboy,  I  formed  the  idea  of  examin- 
ing the  crops  of  birds  at  various  times  of  the  day,  and  at  all 
seasons  of  the  year,  so  as  to  ascertain  the  number  of  insects, 
the  kinds  of  insects,  and  all  other  kinds  of  food  that  they 
devour.  Compelled,  however,  to  live  in  London,  and 
engaged  in  other  matters,  I  ceased  to  pursue  my  plan, 
though  I  saw  facts  amply  sufficient  to  astonish  me  at  the 
vast  collections  of  insects  which  the  crops  of  birds  contain. 

I  would  advise  the  farmer  to  shoot  various  birds  where 
the  vastator  abounds,  and  to  examine  their  crops,  to  ascer- 
tain whether  they  prefer  the  creatures  themselves  or  the 
parasites. 

(428.)  Ducklings,  which  delight  in  eating  little  insects, 
would  also  doubtless  devour  these  destroyers  of  human 
food. 

(429.)  From  the  above  observations,  we  find,  that, 
although  our  most  valuable  vegetables  are  threatened  with 


108  POTATOE    GANGRENE    AND    OTHER    DISEASES. 

destruction  by  a  little  insect,  yet  curiously  enough  our 
hope  of  preservation  from  this  calamity  is  in  a  great 
measure  dependent  upon  the  operations  of  another  insect 
even  more  minute. 


CHAPTER  XIX. 

RELATION    OF    THE    GANGRENE     TO     OTHER    DISEASES    OF    THE 
POTATOE. 

The  curl  (430,  431).— Rollins'  description;  varieties  of  curl  (432— 
434). — Putsche  and  Vertuch's  description  (435). — Curl  probably 
identical  with  present  disease  (436). — Curl  from  attack  of  vastator 
(437).— The  rust  (438). 

(430.)  THE  potatoe  is  affected  with  other  diseases  besides 
the  gangrene,  such  as  the  curl,  &c.  The  curl  was  so 
extremely  prevalent  some  years  ago,  that  the  Society  of 
Arts  awarded  a  premium  for  the  best  remedy. 

(431.)  The  curl,  though  very  common  at  the  commence- 
ment of  the  nineteenth  century,  has  departed  for  many 
years,  so  that  now  we  can  only  know  the  disease  by  re- 
port. 

(432.)  Hollins  describes  the  half-curl,  the  curl,  and  the 
corrupted.  "  The  half-curled  plants  have  leaves  some- 
what long,  and  curl  only  in  a  moderate  degree ;  they  pro- 
duce a  tolerable  crop  if  the  summer  be  not  very  dry;  but 
if  otherwise,  the  produce  will  be  small  and  watery." 

(433.)  "  The  completely  curled  potatoe  plants  are  seldom 
more  than  six  or  seven  inches  high.  They  soon  ripen  and 


POTATOE    GANGRENE     AND    OTHER    DISEASES.  109 

X 

die.  The  potatoes  are  generally  smaller  than  a  nutmeg* 
of  a  rusty-red  color,  and  unwholesome  for  food." 

(434.)  "  The  corrupted  potatoes  are  those  in  which  the 
vegetative  power  is  nearly  destroyed.  These  never  ap- 
pear above  ground.  The  sets  may  be  found  at  Michael- 
mas with  the  same  appearance  as  when  they  were  planted, 
with  a  few  small  potatoes  attached  to  them."* 

(435.)  Putsche.  and  Vertuch  state  "that  the  plants 
which  are  affected  by  this  disease  have  an  extremely 
meagre  appearance.  The  stem  is  unbranched,  brownish- 
green,  or  mottled,  and  here  and  there  sprinkled  with  rusty 
spots,  which  penetrate  to  the  pith  ;  so  that  it  is  not  white, 
but  rust-colored,  or  sometimes  black.  The  upper  surface 
of  the  leaves  is  not  so  smooth  as  usual,  but  rough,  wrinkled, 
curled,  or  crumpled.  The  leaves  are  far  more  sessile 
than  usual,  and  not  of  an  uniform  brownish  or  dark  green, 
but  spotted.  The  passages  for  circulation,  imbibition,  and 
respiration,  are  none  of  them  in  a  healthy  state.  The 
pith  is  often  discolored  or  dried  up,  even  in  the  young 
shoots.  The  starved  plant  often  perishes  early  in  autumn, 
when  the  tubers  should  be  making  their  most  rapid 
growth.  These  tubers  are  scanty  and  tasteless,  juicy  and 
almost  unfit  for  food.  Even  the  color  of  the  outer  coat  of 
the  tuber  is  changed.  The  same  tuber  is  in  parts  brown, 
in  parts  of  a  dirty  yellow,  and  sometimes  the  two  tints  run 
into  each  other.  Some  sorts  of  potatoe  are  more  subject 
to  the  disease  than  others  :  it  is  more  prevalent  in  flat 
countries  than  in  more  elevated  districts."")" 

(436.)  From  these  descriptions,  {  am  much  disposed  to 

*  Trans.  Society  of  Arts. 

f  Martius,  quoted  by  "  Gardener's  Chronicle." 


110  POTATOE    GANGRENE     AND    OTHER    DISEASES. 

believe  that  our  present  gangrene  is  only  an  exaggerated 
form  of  the  old  curl.  It  is  a  common  characteristic  of  the 
numerous  family  of  Aphides  to  render  the  leaf  of  all  plants 
which  they  attack  curled  ;  I  have  frequently  noticed  in 
my  own  sitting-room  that  the  vastator  curls  the  leaf  of 
the  turnip ;  and  it  must  have  been  observed  by  very 
many  how  excessively  distorted  the  leaves  of  the  rose-tree 
become  when  suffering  severely  from  the  ravages  of  the 
Aphis  rosa. 

(437.)  I  have  found,  on  one  or  two  occasions,  a  potatoe 
plant  to  be  covered  with  the  vastator,  and  that,  instead  of 
its  being  destroyed  by  the  insect  in  the  usual  manner,  the 
leaves  exhibited  the  most  exaggerated  form  of  curl  which 
could  be  conceived,  for  they  were  curled  more  than  those 
of  the  most  highly-curled  parsley.  However,  I  feel  un- 
willing to  pass  an  opinion  upon  a  disease  which  I  have 
not  seen  in  its  former  prevalence. 

(438.)  The  rust  is  another  disease.  It  consists  of  a 
colored  spot  upon  the  leaves,  which  is  at  first  small,  but 
gradually  increases,  and  at  length  overruns  the  whole 
leaf.  Of  this  disease,  however,  I  am  practically  ignorant. 


Ill 

CHAPTER  XX. 

THEORY    OF    THE    DISEASE. 

Resume  of  the  various  supposed  causes  of  disease  (439,  440). — 
Vastator  (441).— The  disease  (443). — Condition  of  plant  causing 
death  (444,  445).— Effect  of  disease  on  wild  plants  (446).— On 
cultivated  plants  (447). — Propagation  from  diseased  sets  (448, 
449). — As  to  cessation  of  disease  (450). — Relation  of  health  of 
plant  to  the  insect  (451,  452). 

(439.)  WE  have  now  examined  all  the  various  effects 
which  may  influence  the  potatoe  plant  in  its  growth,  and 
give  rise  to  the  disease.  In  the  course  of  our  investiga- 
tions we  have  found  that  the  action  of  temperature,  light, 
soils,  and  manures,  may  influence  the  plant,  but  positive 
proof  has  been  afforded  that  they  do  not  produce  the  pre- 
sent alarming  epidemic. 

(440.)  It  appears,  moreover,  that  vegetable  parasites 
are  sometimes  present ;  but,  upon  an  attentive  examina- 
tion, there  are  strong  reasons  to  believe  that  they  occur 
after  the  disease  has  been  set  in  action,  and  that  they  grow 
in  the  decaying  matter,  as  a  beautiful  provision  against 
offensive  putridity. 

(441.)  The  case,  however,  is  quite  different  with  the 
animal  parasites  ;  for  we  have  discovered  that  wherever 
the  Aphis  vastator  exists,  there  the  leaves  perish,  there  the 
plant  becomes  injured,  there  its  tubers  and  stems  take  on 
gangrene  and  die,  and  thus  the  disease  is  manifested. 

(442.)  In  this  way  we  have  learnt  the  cause  of  the 
disease,  and  the  theory  of  the  disease  is  easily  ascertained 
from  a  study  of  its  cause. 


112  THEORY    OF    THE    DISEASE. 

(443.)  The  animal  lives  on  the  juices  of  the  plant, 
which  it  extracts  by  means  of  the  apparatus  which  it  in- 
serts into  the  cuticle  of  the  leaf.  This  removal  of  one 
portion  of  the  sap  destroys  its  proper  qualities  ;  it  can  no 
longer  return  the  material  for  the  starch  or  cellular  tissue 
essential  to  the  growth  of  the  plant.  When  the  growth 
of  the  plant  is  arrested,  the  natural  vital  actions  are  im- 
paired, and  other  actions,  as  those  of  putrefaction,  or  inor- 
ganic changes,  take  place  ;  the  plant  ceases  to  live  in 
different  parts,  and  decomposition  ensues. 

(444.)  The  exact  mode  in  which  death  occurs  is  inti- 
mately connected  with  the  most  obscure  functions  of  the 
plant.  Probably  the  sap  continues  to  take  water  from  the 
ground,  but  in  failing  to  receive  sufficient  solid  material 
from  the  leaf,  becomes  altered  and  impaired,  and  thus  the 
plant  is  killed. 

(445.)  The  essence  of  the  disease  is  a  disturbance  of 
the  relation  existing  between  the  leaf  and  the  plant,  and, 
consequently,  the  sap  and  parenchyma  do  not  bear  such 
proper  relation  as  fits  them  for  the  performance  of  the 
vital  functions  ;  and  this  being  the  case,  the  vital  func- 
tions necessarily  cease,  and  the  plant  dies. 

(446.)  The  injury  inflicted  on  wild  plants  is  usually 
confined  to  the  leaf  and  adjacent  stems,  the  roots,  except 
in  very  rank  growers,  being  not  so  much  affected.  In 
this  way  the  plant  may  be  gradually  killed  from  above 
downwards. 

(447.)  We  find  that  cultivated  plants,  where  the  under- 
ground stems  are  highly  developed,  will  not  bear  the  rela- 
tion between  the  stem  and  the  root  to  be  interfered  with  ; 
and  for  this  reason  the  same  number  of  insects  will  exert 


THEORY    OF    THE    DISEASE.  113 

a  far  more  destructive  influence  upon  the  cultivated,  than 
upon  the  wild  plant. 

(448.)  In  plants  which  are  propagated  by  the  mere 
extension  of  the  individual,  as  the  potatoe  is,  the  injury  is 
to  a  great  extent  continued  ;  because,  when  the  relation 
between  the  leaf  and  root,  between  the  fluid  or  sap  and  the 
cellular  tissue  or  solid  parts,  becomes  deranged,  the  plant 
will  propagate  the  same  diseased  relation,  and  consequent- 
ly reproduce  the  same  injury. 

(449.)  The  propagation  of  the  injury  from  set  to  plant 
gives  rise  to  all  those  phenomena  which  I  have  already 
described  when  treating  of  the  potatoe  gangrene,  and  is 
nothing  more  than  a  propagation  of  the  mischief  from  one 
part  of  the  plant  to  another. 

(450.)  In  all  human  probability,  the  disease,  under 
favorable  circumstances,  if  the  cause  be  not  continued,  will 
at  last  wear  itself  out  and  cease ;  but  we  have  not  at 
present  had  sufficient  experience  to  ascertain  this  fact  with 
certainty.  Of  course,  cessation  of  the  disease  will  almost 
absolutely  require  that  the  vastator  shall  not  again  renew 
its  attacks  upon  the  plant. 

(451.)  There  is  an  exquisite  relation  existing  between 
the  effects  upon  the  plant  and  the  welfare  of  the  animal. 
This  creature  cannot  well  live  upon  a  very  vigorous  plant, 
because  it  would  be  drowned  by  the  water  transpired  at 
night.  Hence  it  generally  commences  upon  leaves  which 
have  in  a  great  degree  lost  their  vigor.  On  placing 
insects  upon  the  new  leaves  of  very  vigorous  plants,  I 
have  observed  that  the  creature  has  always  been  obliged 
to  leave  them.  It  commences  upon  the  larger  and  nearly 
exhausted  leaves  ;  from  these  it  passes  to  others,  and  so  on 
till  the  entire  foliage  is  affected. 


114  THEORY    OF    THE    DISEASE. 

(452.)  The  impairment  of  the  health  of  the  whole  plant 
might  lead  us  to  suppose  that  it  would  cause  the  destruc- 
tion of  the  creature.  Not  so,  however  ;  Nature  has 
wonderfully  ordained  that  the  exhaustion  of  the  plant 
should  have  an  influence  upon  the  animal.  When  the 
plant  no  longer  retains  sufficient  vigor  to  supply  nourish- 
ment to  the  insect,  the  creature  ceases  to  reproduce,  it 
takes  the  pupa  form,  and  finally  emerges  from  that  transi- 
tory condition  in  its  final  or  more  glorious  state,  when 
countless  millions,  in  the  form  of  a  cloud,  take  flight,  soar 
aloft,  and  traverse  mountains,  valleys,  streams,  lakes,  seas, 
and  even  kingdoms,  destroying  in  their  progress  some  of 
the  most  useful  foods  of  man.* 

(453.)  Such  beautiful  illustration  of  the  perfection  of 
nature  almost  compels  the  naturalist  for  a  time  to  forget 
the  great  calamity  which  has  happened  to  the  human  race 
by  this  little  insect.  This  minute  creature,  which  by 
itself  may  appear  to  be  scarce  worth  our  notice,  when 
congregated  in  masses,  becomes  an  army,  terrible  and 
invincible  even  to  the  English  nation.  Napoleon,  with  all 
his  army,  with  all  his  bravery,  never  dared  set  foot  on  the 
English  shore  :  this  little  insect  has  baffled  science,  poli- 
tics, and  power  ;  it  has  invaded  our  territories,  it  has,  in 
spite  of  all  our  armies,  fleets,  and  forts,  come  into  our 
lands,  and  taken  from  our  possessions  the  food  destined  to 
nourish  our  children. 

*  This  destroying  cloud,  wafted  about  with  the  winds,  settles 
here  and  there  upon  some  ill-fated  locality :  hence  the  prevalence 
of  a  wind  in  one  direction  may  influence  to  a  great  extent  the  more 
or  less  extensive  damage  in  various  aspects. 


115 
CHAPTER  XXI. 

FUTURE    PROSPECTS    OF    THE    DISEASE. 

Mischief  done  to  esculent  vegetables,  &c.,  by  vastator  (454). — Dura- 
tion of  insect  pests  :  historical  analogies  (455). — Probabilities  as 
to  increase  of  the  plague  (456,  457). — Aphis  brassicae  (458). — 
Insect  destroyers  of  vastator  (459).— Probable  result  of  disappear- 
ance of  vastator  (460) ;  of  continuance  (461)  ;  of  increase  (462). — 
Concluding  remarks  (463). 

(454.)  WE  have  now  seen  that  the  gangrene  of  the 
potatoe  is  caused  by  the  injury  done  to  the  plant  by  a 
small  insect  which  has  appeared  in  great  abundance,  and 
which  attacks  also  the  turnip,  tfye  beet,  the  carrot,  the 
different  Solani,  various  Cruciferse,  wheat,  and  Indian 
corn. 

(455.)  Upon  examining  historical  records,  we  have  also 
found,  that  when  an  insect  has  appeared  in  great  excess,  it 
has  generally,  after  a  time,  disappeared,  and  the  balance 
of  nature  has  been  again  maintained. 

(456.)  In  the  present  instance,  however,  although  we 
have  seen  whole  clouds  of  these  Aphides, — although  they 
exist  by  countless  millions,  yet  we  are  not  at  all  in  a 
position  to  state  that  they  have  reached  their  climax. 

(457.)  It  is  possible  that  they  may  continue  for  some 
time  longer,  and  that  next  year  they  may  destroy  not  only 
the  various  vegetables  which  have  hitherto  been  their 
prey,  but  may  even  annihilate  the  wheat. 

(458.)  The  excessive  appearance  of  this  Aphis  this 
year  is  not  a  singular  fact,  for  the  Aphis  brassica  exists  in 
such  abundance,  that  thousands  are  to  be  found  on  the 


116  FUTURE    PROSPECTS   OF    THE    DISEASE. 

leaves  of  plants  sent  to  market ;  but  it  is  strange  that  the 
Aphis  of  the  hop  has  done  but  little  or  no  mischief  this 
season. 

(459.)  To  suppose  that  the  Aphis  vastator  will  con- 
tinue to  increase,  and  cause  actual  famine,  is  to  look  at 
the  dark  side  of  the  question,  for  we  may  hope  that  it  has 
already  reached  its  utmost  limit. 

This  is,  however,  a  question  which  time  only  can  settle, 
and  we  must  look  anxiously  for  troops  of  ichneumons  and 
legions  of  lady-birds  to  come  and  eat  up  the  all-devouring 
creatures. 

(460.)  Supposing  that  the  ravages  of  the  insect  cease 
or  stop  to  a  great  extent,  yet,  however,  the  potatoe  is  dis- 
eased, and  will  grow  diseased  plants  for  some  little  time. 
I  think,  however,  that  we  need  be  in  no  fear  of  permanent 
damage  from  this  cause,  for  in  all  probability,  the  malady, 
under  favorable  circumstances,  will  wear  itself  out ;  and 
certainly,  by  industry,  we  may  easily  overcome  this 
difficulty.  If  the  disease  does  not  stop  when  the  insect 
departs  from  the  potatoe,  we  have  but  to  commence  with 
sets  derived  from  the  sound  tuber  to  obtain  new  crops  ;  so 
that  eventually  we  should  be  enabled  to  renovate  our 
stores  with  good  seed. 

(461.)  It  is  appalling,  however,  to  consider  the  dark 
side  of  the  question  ;  for  a  continuance  of  the  action  of  the 
insect  upon  the  stalks  of  the  diseased  tuber  would  render 
the  plants  still  further  diseased  ;  and  if  that  be  assisted  by 
cold  and  moist  weather,  the  crop  may  be  nearly  annihi- 
lated. 

(462.)  Moreover  the  insect  is  still  on  the  increase  ;  it 
was  more  abundant  this  year  than  the  year  before ;  and, 
judging  by  its  effects,  still  more  numerous  than  the  year 


FUTURE    PROSPECTS    OF    THE    DISEASE.  117 

previous  to  that.  We  know  it  only  in  its  progressive 
character,  and  we  might  even  possibly  have  it  ten  times 
more  numerous  next  year,  and  it  might  destroy  to  a  ten- 
fold greater  extent  our  usual  sources  of  food.  Should  this 
nation  of  destroyers  appear  next  year  much  earlier  than  it 
has  heretofore,  it  may  produce  the  most  disastrous  results 
by  killing  all  the  most  serviceable  kinds  of  human  food. 

(463.)  Upon  the  whole,  let  us  buoy  ourselves  up  with 
the  hope  that  the  plague  has  reached  its  utmost  limit,  that 
it  may  speedily  cease,  and  that  its  effects  are  merely  tran- 
sitory. Let  the  husbandman  be  of  good  cheer,  and  remem- 
ber, that  if  nature  deviates  for  a  time  from  its  wonted 
relations,  it  always  returns  to  its  normal  condition,  and 
ultimately  maintains  the  proper  balance  of  animated  beings. 
Let  all  people  remember  the  promise  in  Malachi,  "  that 
God  will  rebuke  the  devourer  for  your  sakes,  and  he  shall 
not  destroy  the  fruits  of  your  ground." 


118 


CHAPTER  XXII.     ; 

ARTIFICIAL    REMEDIES    FOR    THE    POTATOE    DISEASE. 

Division  of  subject  (464). — Destruction  of  Aphis  considered  :  by 
human  means  (465) ;  by  tobacco  (466).— Effects  of  water,  thunder- 
storm, on  Aphis  rosae  (467) ;  on  vastator  ("468).—  Burning  infected 
leaves  (469).— Effect  of  leaf-burning  in  beet  (470).— Quicklime 
(471).— Ducks  and  soft-billed  birds  (472).— Coccinellae  and  ich- 
neumons (473).— Wheat  (474).— Early  ripening  (475).— Early 
potatoes  (476).— Autumn  planting  (477).— Recapitulation  (478). — 
Contagion  (479).— Burning  infected  haulms  (480).— Isolation  of 
crops  (481).— Means  to  be  adopted  over  large  districts  (482). — 
Same  means  for  all  crops  (483). — Propagation  from  healthy  sets 
(484). — Generation  of  fibre  (485). — Means  of  inducing  this  (486). 
—Sets  (487).— Varieties  resembling  the  wild  potatoe  (488).— 
Planting  in  sand  or  peat  (489). — Dryness,  warmth,  and  light 
(490). — Propagation  of  the  young  stalks  (491,  492).— Requisites 
for  healthy  propagation  (493,  494).— Diminished  starch  (495).— 
Starch  cells  (495).— Remedies  which  have  been  proposed  (497).— 
Drying  (498).— Cold  and  dryness  (499).— Review  (500). 

(464.)  THE  artificial  remedies  to  be  adopted  to  lessen  the 
potatoe  malady  may  be  divided  into  four  great  classes. 
One  class  comprises  those  means  which  we  should  take  to 
lessen  the  numbers  of  the  insect,  and  thus  strike  at  the  root 
of  the  cause.  The  second  class  contains  the  treatment  to 
be  pursued  for  stopping  the  contagion.  The  third  class 
comprises  those  remedies  which  are  destined  to  prevent  the 
continuance  of  the  disease  in  the  infected  plant;  and, 
lastly,  we  have  to  consider  a  fourth  class,  where  we  desire 
to  lessen  the  baneful  agency  of  the  malady  when  it  has 
actually  occurred. 


ARTIFICIAL    REMEDIES    FOR    DISEASE.  119 

REMEDIES    AGAINST    THE    CAUSE. 

(465.)  The  absolute  destruction  of  the  Aphis  by  human 
means  is  doubtless  an  impossibility,  and  the  only  means 
which  we  could  adopt  would  be  to  destroy  the  insect  the 
moment  it  appeared  upon  the  potatoe  plant.  This  simple 
remedy  is,  however,  exceedingly  difficult  to  apply,  even 
when  we  wish  to  protect  a  single  plant.  I  had  an  infested 
plant  in  a  pot  at  Finsbury  Circus,  and  though  I  frequently 
tried  to  eradicate  the  insect,  yet  there  was  continually 
some  one  or  other  left ;  for  these  little  rascals  crawl  into 
chinks  and  crannies,  from  which  they  come  forth  at  their 
convenience,  and  rapidly  multiply. 

(466.)  If  the  protection  of  a  single  plant  be  so  difficult, 
how  much  more  so  must  be  the  protection  of  the  potatoe 
plants  covering  large  tracts  of  land  ?  We  must  conduct 
our  campaign  against  the  destroyer  in  this  case  by  adopt- 
ing a  more  wholesale  remedy.  On  the  small  scale,  the 
infusion  or  vapor  of  tobacco  would  destroy  them,  but  it 
would  be  impossible  for  the  agriculturist  to  employ  that 
remedy  over  large  fields. 

(467.)  Many  kinds  of  Aphides  are  destroyed  by  water, 
and  I  had  to  lament  the  loss  of  several  pet  colonies  of  the 
Aphis  rosce,  which  were  destroyed  by  the  rain  of  a  thunder- 
storm ;  and  it  is  said  that  the  hop  plantations  of  the  whole 
county  of  Kent  may  be  cleared  of  their  Aphides  by  a  single 
thunder-storm.  The  cultivators  of  rose-trees  practically 
syringe  the  infested  trees,  and  so  get  rid  of  their  pest. 

(468.)  Neither  water  nor  thunder-storms  seem  to  have 
much  influence  upon  the  vastator,  further  than  that  the 
electricity  seems  to  occasion  a  great  migration  of  these 
creatures.  The  vastator  appears  to  cling  very  tightly  to 


120  ARTIFICIAL    REMEDIES    FOR 

the  plant  by  the  suctorial  apparatus  contained  in  the  inte- 
rior of  the  rostrum,  and  its  feet,  too,  seem  well  calculated 
to  assist  it  in  maintaining  its  position.  Moreover,  the  de- 
stroyer lives  generally  at  the  under  surface  of  the  leaf,  so 
that  the  leaf  serves  it  as  an  umbrella  to  ward  off  the  fluid. 

(469.)  It  would  certainly  be  a  good  plan,  in  many  cases, 
to  gather  those  leaves  which  are  infested  with  the  insects, 
and  to  burn  them,  before  the  creature  has  made  any  ex- 
tensive progress.  New  leaves  would  doubtless  be  thrown 
out  of  the  haulm ;  but  this  mode  of  proceeding  would  only 
be  applicable  to  a  very  small  extent  in  the  potatoe  plant. 

(470.)  With  regard  to  beet  root,  however,  I  am  decided- 
ly of  opinion  that  the  removal  of  the  infected  leaves  is 
the  best  course  to  be  pursued.  If  they  are  left  on  the 
plant  they  perish,  and  thus  become  unserviceable ;  where- 
as, if  they  are  removed  before  extensive  mischief  has  been 
effected  in  the  tissue,  they  may  still  afford  useful  nourish- 
ment to  cattle.  As,  moreover,  the  insect  first  attacks  the 
larger  and  more  exhausted  leaves,  we  should  thus  destroy 
masses  of  insects,  which  would  otherwise  progress  to  other 
and  more  important  leaves. 

(471.)  The  action  of  quicklime,  sprinkled  dry  over  the 
plants,  is  said  to  be  particularly  destructive  to  the  Aphides; 
and  I  have  seen  several  notices  in  the  papers  where  persons 
had  sprinkled  lime  empirically  over  the  haulms  the  moment 
the  disease  appeared,  which  arrested  the  progress  of  the 
disease.  This  proceeding  I  should  recommend  to  be  largely 
tried,  by  sifting  fine  quicklime  over  plants  as  soon  as  the 
vastator  appears.* 

*  Perhaps  also  various  saline  matters  might  be  employed  for  the 
same  object. 


THE    POTATOE    DISEASE.  121 

(472.)  We  might  perhaps  try  the  experiment  of  rearing 
large  quantities  of  ducks,  and  turning  them  loose  in  infect- 
ed fields  to  eat  the  vermin,  as  by  that  means  we  should 
convert  the  destroying  insect  into  a  source  of  profit  to  our- 
selves. It  would  be  perhaps  especially  advisable  to  enacit 
laws  to  prohibit  the  destruction  either  of  the  soft-billed 
birds  or  their  eggs,  as  the  number  of  insects  they  devour 
is  almost  incredible. 

(473.)  It  would  be  impossible  practically  to  breed  lady- 
birds and  ichneumons  on  any  other  but  a  very  small  scale, 
but  we  should  be  very  careful  to  preserve  these  valuable 
natural  devourers  of  the  Aphides. 

(474.)  Should  the  wheat  become  seriously  attacked,  I 
really  know  not  what  remedy  can  be  applied  to  destroy 
the  creature ;  but  I  am  in  hopes  that  such  may  not  be  the 
case,  or  rather  that  the  grain  may  be  too  forward  when  the 
pest  appears,  to  be  extensively  damaged  by  it. 

(475.)  In  considering  the  means  to  be  adopted  for  the 
prevention  of  the  disease,  we  should  bear  in  mind  that  the 
creature  has  not  come  hitherto  in  great  abundance  till  July 
or  August ;  hence,  if  we  could  get  the  plants  ripe  before 
that  period,  we  should  cheat  the  insect  of  his  spoil.  It  is 
impossible  to  tell  how  much  earlier  the  insect  may  appear 
another  year ;  but,  as  we  can  only  act  for  the  future  by 
the  consideration  of  the  past,  it  would  be  advisable  to  use 
such  plants  as  render  their  produce  early. 

(476.)  With  respect  to  the  pptatoe,  the  use  of  the  early 
kinds  is  most  strongly  to  be  commended  ;  and  these  should 
be  employed,  during  the  prevalence  of  the  disease,  as  much 
as  possible  to  the  exclusion  of  the  late  varieties. 

(477.)  Johnson  strongly  recommends  autumn  planting 
as  a  means  of  preserving  the  potatoe  plant  against  the 

6 


122  ARTIFICIAL    REMEDIES    FOR 

disease ;  but  I  have  found  thousands  of  plants  damaged 
which  had  been  left  in  the  ground  all  the  winter  from  pre- 
vious crops.  Hence,  taken  by  itself,  this  plan  forms  no 
protection,  though,  by  tending  to  forward  the  growth  of 
the  plant,  it  may  help  to  cheat  the  destroyer,  and  lessen 
the  mischief. 

(478.)  The  best  means  of  destroying  the  cause  is  to 
pick  off  the  insect  when  we  desire  to  protect  a  single  plant. 
To  pull  off  affected  leaves,  or  to  sprinkle  them  with  quick- 
lime, when  we  wish  to  protect  a  larger  number  of  plants. 
We  should  endeavor  to  get  our  produce  ripe  at  an  early 
period  by  using  early  kinds,  and  by  planting  early,  perhaps 
even  in  autumn.  We  should  protect  lady-birds,  ichneu- 
mons, and  soft-billed  birds ;  and  we  may  try  the  effect  of 
ducks  to  gobble  up  the  parasites. 


REMEDIES    AGAINST    CONTAGION. 

(479.)  We  must  remember  that  the  mischief  is  eminent- 
ly contagious,  and  that  the  destroyer  may  spread  from  one 
crop  to  another  j  therefore,  especial  care  should  be  taken 
to  prevent  contagion.  I  have  often  traced  the  disease  in  tur- 
nips to  their  proximity  to  potatoes,  disease  in  beet  to  its 
proximity  to  turnips  ;  and  I  have  traced  the  disease  radiat- 
ing from  old  infected  haulms  heaped  together  for  manure. 

(480.)  Whenever  potatoes  are  dug  up,  the  infected 
haulms  should  be  instantly  burnt,  in  order  to  destroy  the 
insect ;  and,  perhaps,  it  would  be  a  good  plan  when  we 
find  even  the  living  haulms  excessively  affected,  at  once 
to  pull  them  up  and  burn  them.  Marshall  has  long  ago 
proved  that  cutting  down  the  haulm  lessens  the  crop  of 


THE    POTATOE    DISEASE.  123 

tubers,  and  Mr.  Thompson  tells  me,  that  when  the  haulm 
was  pulled  up  at  the  Horticultural  Society's  Gardens,  the 
crop  of  tubers  was  less  and  the  disease  was  worse.  This 
plan  is  not,  however,  to  be  adopted  for  the  benefit  of  the 
plant  itself,  but  only  for  the  purpose  of  destroying  vast 
nations  of  the  Aphides. 

(481.)  Every  wise  farmer  would  isolate  the  crops  which 
are  liable  to  be  affected  by  the  malady.  He  would  not 
plant  turnips,  potatoes,  beet-roots,  and  carrots  in  the  same, 
or  even  in  contiguous  fields,  but  would  distribute  them 
over  his  farm  as  widely  as  circumstances  will  allow.  The 
very  worst  case  of  the  malady  I  ever  saw  was  in  a  very 
small  field,  where  potatoes,  beet-roots,  and  turnips,  were 
planted  together.  In  this  case  the  insects  on  the  beets  ex- 
isted in  countless  legions. 

(482.)  All  remedies  of  this  character,  to  be  of  any 
value,  must  be  universal ;  as  a  partial  attempt  to  remedy 
contagion  could  be  of  but  little  benefit.  The  winged 
insect  can  fly  from  field  to  field,  from  parish  to  parish,  and 
even  from  kingdom  to  kingdom  ;  and  when  it  attacks  it 
multiplies  with  fearful  rapidity.  In  order  successfully  to 
attempt  the  extermination  of  this  pest,  therefore,  a  whole 
country,  or  even  all  Europe,  must  devote  its  best  energies 
to  the  cause.  An  occasional  obstinate,  pig-headed  farmer 
ought  not  to  be  allowed  to  act  contrary  to  the  welfare  of 
the  whole  country  ;  and,  perhaps,  therefore,  power  might 
very  advantageously  be  given  to  churchwardens,  or  other 
official  persons,  to  adopt  measures  best  calculated  to  cut 
off  contagion. 

(483.)  The  observations  which  I  have  just  made  have 
appertained  chiefly  to  the  potatoe ;  but  it  will  readily  be 
seen  that  they  apply  equally  to  the  prevention  of  contagion 


124  ARTIFICIAL    REMEDIES    FOR 

in  all  other  crops  which  are  liable  to  be  attacked  by  the 
malady,  and  all  these  measures  should  be  employed  in  the 
spring. 


REMEDIES    AGAINST    PROPAGATION. 

(484.)  The  different  varieties  of  potatoes  are  now  dis- 
eased in  most  situations,  and  we  have  found  that  the  malady 
is  continued  in  future  growths  of  the  same  individual.  To 
prevent  the  propagation  of  the  disease,  without  respect  to 
a  repetition  of  the  cause,  we  have  but  to  use  sets  from 
former  perfectly  undiseased  plants,  and  unless  the  insect 
again  appear,  the  plant  which  grows  from  such  sets  will 
be  healthy. 

(485.)  As  the  attack  of  this  creature  operates  principally 
by  causing  deficiency  of  the  solid  materials  of  the  plant, 
we  ought,  if  we  desire  to  check  the  disease,  to  do  every- 
thing in  our  power  which  conduces  to  the  generation  of 
fibre. 

(486.)  With  this  object  in  view,  the  plant  should  not  be 
encouraged  to  throw  out  large  succulent  shoots  in  its  early 
growth,  but  should  rather  throw  out  dry  and  arid  shoots  : 
in  fact,  the  sort  of  treatment  which  would  render  other 
plants  strong  and  fibrous  would  probably  tend  to  render  the 
potatoe  sound. 

(487.)  I  should  be  inclined  to  try  the  experiment  of 
using  but  small  portions  of  the  potatoe  for  sets,  such  as 
scooped  eyes,  or  potatoe  peelings,  although  Marshall  has 
ascertained,  that,  under  ordinary  circumstances,  the  crop 
is  thereby  materially  lessened.  These  means  would  only 


THE    POTATOE    DISEASE.  1*25 

be  serviceable  to  restore  the  health  of  a  diseased  plant, 
not  to  arrest  the  malady  at  its  commencement. 

(488.)  Perhaps  it  would  be  advisable  to  return  as  far 
as  possible  for  a  time  to  the  cultivation  of  those  plants 
which  most  nearly  approximate  in  character  to  the  wild 
plant ;  especially  as  we  find  that  wild  plants  in  general, 
and  the  assumed  wild  potatoe  plant,  resist  much  more 
effectively  the  ravages  of  the  disease  than  the  more 
highly  cultivated  varieties. 

(489.)  It  has  been  currently  stated,  that,  by  planting 
potatoes  in  sand  or  peat,  the  disease  has  been  lessened, 
and  probably  it  would  be  sound  philosophy  to  place  the 
tuber  under  circumstances  which  may  induce  it  to  return 
as  far  as  possible  towards  its  original  condition. 

(490.)  The  exposure  of  the  plant  to  a  dry  atmosphere, 
to  a  good  temperature,  and  to  abundance  of  light,  would 
also  doubtless  assist  in  regenerating  the  plant,  provided  the 
insect  does  not  again  come  and  injure  it. 

(491.)  Perhaps  it  might  be  advisable  to  allow  the  stalk 
to  grow  from  the  tuber  two  or  three  inches  high,  and  then 
to  detach  it  and  use  it  as  a  set.  By  this  plan  we  should 
throw  the  potatoe  plant  for  its  resources  upon  the  leaves, 
and  not  upon  the  original  set ;  and,  doubtless,  by  attend- 
ing to  other  circumstances  influencing  the  result,  we 
should  thus  place  the  plant  in  a  good  condition  for  regene- 
rating its  fibre. 

(492.)  One  potatoe  tuber,  upon  this  plan,  would  send 
forth  numerous  shoots,  and  thus  a  great  saving  would  be 
effected  in  the  amount  of  potatoes  used  for  seed.  We 
may  expect  from  the  experiments  of  Marshall  that  this 
course  would  lessen  the  produce,  and,  therefore,  this 
method  would  only  appertain  to  the  regeneration  of  the 


126  ARTIFICIAL    REMEDIES    FOR 

potatoe  plant,  with  the  view  of  obtaining  again  healthy 
seed  from  which  to  propagate  our  plants. 

(493.)  It  is  doubtless  upon  this  plan,  that  a  mere  eye, 
left  from  a  thoroughly  rotten  potatoe,  has  been  found  to 
produce  sound  tubers ;  as  the  plant,  in  this  case,  is  from 
the  very  commencement  thrown  upon  its  own  resources, 
and  has  to  form  its  own  starch  and  fibre  from  the  leaves, 
instead  of  drawing  at  first  diseased  material  from  the  set. 

(494.)  For  the  regeneration  of  a  diseased  plant  we 
should  employ  dry,  poor,  unmanured  soil ;  we  should  use 
small  sets,  and  should  have  a  dry  and  warm  atmosphere. 


REMEDIES    AGAINST    THE    CONSEQUENCES. 

(495.)  We  have  now  to  consider  the  best  modes  of 
averting  the  consequences  of  the  malady  in  the  tuber. 
The  starch  which  has  been  formed  still  exists  in  the  dis- 
eased tuber,  but  in  bad  cases  very  little  even  of  that 
material  is  formed  ;  and  no  doubt  the  quantity  of  starch  to 
the  acre  under  cultivation  is  enormously  diminished.  It 
is  possible  practically  to  extract  the  starch,  and  preserve 
it  for  fattening  cattle  or  for  use  in  the  arts. 

(496.)  It  is  quite  manifest  that  we  can  do  nothing  to 
increase  the  starch  in  the  empty  cells,  and,  therefore,  we 
can  only  preserve  that  which  is  already  existing.  The 
cells  have  a  tendency  to  become  broken  down  and  useless, 
and  the  nitrogenized  portion  is  liable  to  decompose. 

(497.)  I  have  already  mentioned  that  in  potatoes  and 
other  vegetables  tending  to  rot  from  the  present  disease, 
the  disorganization  continues  even  when  the  plants  are 
quite  protected  from  the  atmosphere  ;  and,  therefore,  we 


THE    POTATOE    DISEASE.  1*27 

cannot  do  much  to  lessen  the  mischief  on  this  score.  It 
has  been  proposed  to  dip  slices  of  potatoe  in  dilute  sul- 
phuric acid,  but  it  is  useless  as  a  practical  treatment.  It 
has  been  proposed,  too,  to  expose  the  tubers  to  chlorine,  but 
that  also  appears  quite  out  of  the  question.  If  any  chemi- 
cal means  are  to  be  employed,  I  should  recommend  the 
vapor  of  strong  pyroligneous  acid  ;  but  I  have  no  faith  in 
any  chemical  remedy. 

(498.)  It  has  been  said  that  by  simply  pinching  or  cut- 
ting a  potatoe  the  disease  is  arrested ;  but  this  surely 
must  be  a  mistake,  as  I  have  observed  the  malady  proceed 
to  total  disorganization  even  in  a  thin  section  in  a  dry 
room.  Potatoes  might  be  dried,  and  thus  preserved  like 
the  maglia  of  the  Peruvians  ;  but  perhaps  this  process  is 
not  practically  so  useful  as  the  extraction  of  the  starch. 

(499.)  Perhaps,  however,  there  is  no  plan  for  the  pre- 
servation of  the  potatoe  at  all  equal  to  simply  placing  it  in 
a  cold,  dry  atmosphere  ;  and  from  this  we  may  learn  that 
potatoes  should  never  be  kept  in  large  masses,  whereby 
they  are  liable  to  become  heated  ;  for  in  fact  everything 
that  favors  putrefaction  helps  the  progress  of  the  disease, 
everything  that  prevents  decomposition  retards  the  action 
of  the  malady. 

(500.)  In  taking  a  review  of  the  remedies  for  the 
potatoe  disease,  we  have  found  that  it  is  of  fundamental 
importance  to  stop  the  cause  by  destroying  the  insect,  and 
preventing  the  spread  of  the  contagion.  Secondly,  we 
have  considered  the  best  means  of  stopping  the  propaga- 
tion of  the  mischief;  and,  lastly,  we  have  endeavored  to 
ascertain  the  best  treatment  for  curtailing  the  mischief  of 
the  disease  in  the  tuber. 


128 
CHAPTER  XXIII. 

ON    FAMINES. 

Equalization  of  food  (501). — Deficient  crops  (502).— Enumeration 
of  famines  (503). — Inefficient  legislation  as  to  public  health 
(504). — Proposed  remedy  (505). — Duties  of  a  council  of  health 
(50t> — 508). — Precautionary  measures  (509). — Absolute  duties  of 
the  executive  (511 — 512). — Table  of  esculents  attacked  by  vastator 
and  other  aphides  (513). — Other  nutritive  matter  (514 — 517). — 
Excise  laws  (518) ;  the  year  1845  (519)  ;  1846  (520).— Conclud- 
ing remarks  (521—522). 

(501.)  IN  former  periods  of  the  world  famines  were 
more  frequent  than  at  the  present  time,  because  the  means 
of  equalizing  the  food  were  more  imperfect.  Now,  how- 
ever,  railways,  steamers,  and  ships,  can  soon  carry  abun- 
dance from  the  land  of  plenty  to  those  regions  where 
scarcity  and  famine  exist. 

(502.)  The  following  list  of  famines  will  show  that  the 
world  has  suffered  from  scarcity  of  food,  and  no  doubt  may 
suffer  again  from  a  similar  cause,  should  a  great  portion 
of  the  globe  have  deficient  crops  : — 

(503.)  A  famine  which  lasted  seven  years  1708  B.  c.  at 
Rome,  when  many  persons  threw  themselves  into  the  Tiber ; 
B.  c.  440,  in  Britain,  so  that  the  inhabitants  ate  the  bark  of 
trees ;  A.  D.  272,  one  in  Scotland,  when  thousands  were 
starved  ;  306,  in  England  and  Wales,  when  40,000  were 
starved;  310,  .all  over  Britain;  325,  at  Constantinople; 
446,  in  Italy,  when  parents  ate  their  children  ;  450,  in 
Scotland  ;  376,  all  over  England,  Wales,  and  Scotland  ; 
739,  another  in  Wales;  747,  in  Wales  and  Scotland  ;  792, 
again  in  Scotland  ;  803,  again  in  Scotland,  when  thousands 
were  starved ;  823,  a  severe  one  in  Wales ;  836,  in  Scot- 


ON    FAMINES.  129 

land,  which  lasted  four  years ;  954,  famines  in  England  ; 
864,  974,  1005,  in  Scotland,  which  lasted  two  years ;  1047, 
in  England  ;  1050,  1087,  in  England  ;  a  famine  from  1193 
to  1195,  which  led  to  a  pestilential  fever,  in  England; 
1251,  one  so  dreadful  that  the  people  devoured  the  flesh  of 
horses,  dogs,  cats,  and  vermin ;  again  in  1315,  1318,  1335, 
1345,  in  England  and  France,  called  the  "  dear  summer ;" 
1353,  in  England  ;  1389  and  1438,  so  great  that  bread  was 
formed  of  fern  roots ;  in  1565,  two  millions  were  expended 
on  the  importation  of  corn ;  one  in  1748,  at  the  Cape  de 
Verds,  when  16,000  persons  perished ;  1775,  another  in 
England ;  in  1798,  again  throughout  the  kingdom ;  in 
1801,  scarcity  in  Ireland,  again  in  1814,  1816,  1822, 
1831. 

(504.)  In  this  country  we  are  governed  by  individuals 
of  three  classes,  viz.,  by  men  whose  duty  it  is  to  provide 
for  the  welfare  of  the  soul ;  by  those  whose  profession  it  is 
to  protect  person  and  property ;  and  by  a  third  class,  who 
possess  their  right  by  virtue  of  their  ancestors.  Those, 
however,  who  protect  the  body,  are  allowed  to  take  no  part 
in  the  great  councils  of  the  state  ;  and  even  Jenner,  Hunter, 
and  Harvey,  remained  in  their  private  capacity.  From 
this  cause  the  living  remain  amongst  the  exhalations  of  the 
dead  ;  deleterious  and  poisonous  adulterants  are  suffered  to 
exist  in  our  food  ;  and  habits  of  life  are  allowed  which  are 
in  the  highest  degree  prejudicial  to  the  welfare  of  the  com. 
munity. 

(505.)  To  prevent  this,  a  council  of  health  might  be  ap- 
pointed to  watch  and  report  upon  all  external  causes  which 
can  possibly  affect  the  bodily  health  of  the  community. 

(506.)  The  duty  of  such  a  council,  at  the  present  time, 
would  be  to  ascertain  what  food  is  to  be  procured,  and  how 

6* 


130  ON    FAMINES. 

it  can  be  best  economized.  Moreover,  they  should  prevent 
the  employment  of  unwholesome  food,  and  should  take  great 
care  that  all  other  external  circumstances  should  as  far  as 
possible  be  so  regulated  that  the  pestilence  attending  upon 
famine  may  be  averted,  and  that  fever,  diarrhoea,  sickness, 
and  excessive  mortality,  may  be  prevented. 

(507.)  When  we  know  not  whether  this  disease  be  still 
increasing,  it  would  behove  such  a  council  to  be  stirring ; 
to  have  weekly  reports  upon  the  progress  of  the  insects 
from  different  parts  of  the  kingdom ;  to  do  their  best  to  cut 
short  the  cause  of  the  malady ;  to  apply  new  materials  for 
human  food  ;  and  to  take  care  that  such  an  economy  of  nu- 
tritious material  be  enforced,  that  no  man  should  suffer  from 
want  of  proper  food. 

(508.)  All  these  conditions  might  a  properly  educated 
council  of  health  fulfil ;  and,  until  this  be  accomplished, 
never  will  pestilence,  famine,  adulterated  and  damaged  food 
be  prevented  from  exercising  their  deleterious  agency  upon 
society. 

(509.)  Next  year  will  be  a  very  anxious  period,  as  we 
are  already  using  our  old  supplies  of  food.  If,  therefore, 
the  insect  continue  to  increase,  it  will  be  desirable  to  have 
reports  from  all. parts  of  the  habitable  globe,  upon  the  quan- 
tity of  surplus  food  existing,  that  we  may  know  at  once 
where  to  apply. 

(510.)  It  is  absurd  to  suppose  that  it  is  the  duty  of  Gov- 
ernment to  supply  food,  except  under  extraordinary  circum- 
stances. It  is,  moreover,  impossible  that  Government  can 
keep  down  artificially  the  price  of  bread  for  any  time,  with- 
out the  most  disastrous  results. 

(511.)  To  Government  we  have  no  business  to  look  for 
our  actual  supplies  of  food,  though  the  executive  is  clearly 


ON    FAMINES. 


131 


responsible,  in  cases  of  famine,  to  give  the  best  principles 
to  be  pursued  for  the  alleviation  of  the  misery.  They  ought 
to  know  beforehand  where  food  is  deficient;  they  ought  to 
know  where  food  is  in  excess ;  and  they  ought  to  know  the 
kind  of  food  which  should  be  imported  to  remedy  the  mis- 
chief. 

(512.)  Private  individuals,  private  enterprise,  must  and 
would  do  the  rest,  if  the  price  of  provisions  were  not  artifi- 
cially tampered  with.  The  more  the  executive  regulates 
the  principles,  and  the  less  it  regulates  the  practice  of  the 
supply  of  food,  the  better  will  be  the  result  permanently 
for  mankind  in  general. 

(513.)  If  we  regard  the  following  list  of  alimentary  sub- 
stances given  by  Pereira,  we  shall  be  enabled  to  form  a 
feeble  idea  of  the  ravages  which  the  vastator  may  commit.* 
If,  moreover,  we  regard  how  large  a  proportion  of  the  re- 
mainder are  attacked  by  other  Aphides,  the  numbers  of 
which  are  influenced  by  the  vastator,  we  may  form  a  more 
correct  estimate  of  the  terrible  injury  which  the  vastator 
may  effect. 


Wheat  V. 

Plum  A. 

Pumpkins. 

Asparagus. 

Oats  A. 

Cherry. 

Tamarinds. 

Cabbage  V. 

Barley  A. 

Olive. 

French  beans. 

Savoy  V. 

Rye  A. 

Apples  A. 

Scarlet  beans  A. 

Greens  V. 

Maize  V. 

Pears. 

Figs. 

Cauliflower  V. 

Peas  A. 

Quinces. 

Mulberries. 

Brocoli  V. 

Beans  A. 

Currants. 

Pine-apple. 

Spinage  V. 

Lentils. 

Gooseberries. 

Strawberries. 

Mustard  V, 

Chestnuts. 

Cranberries. 

Raspberries. 

Lettuce. 

Walnuts. 

Elderberries  V. 

Blackberries. 

Endive. 

*  The  items  marked  V  are  those  which  the  vastator  has  attacked  ; 
those  marked  A  are  those  attacked  by  other  Aphides. 


132  ON    FAMINES. 

Hard  nuts.  Grapes.  Turnip  V.  Rhubarb. 

Cobed  nuts.  Oranges.  Carrot  V.  Garden      arti- 

Pistachio  nuts.  Lemons.  Parsnip  V.  choke  V  ? 

Stone  pine  nuts.  Citrons.  Jerusalem  arti-  Fern  root. 

Cocoa  nuts.  Shadocks.  choke  V.  Iceland  moss. 

Almonds.  Cucumbers.  Potatoe  V.  Ceylon  moss. 

Peach  V.  Melons.  Leeks.  Mushroom. 

Nectarine  V.  Water-melons.     Garlic.  Morel. 

Apricot.  Mallows.  Shallots.  Truffle. 

(514.)  In  this  list  of  vegetables  used  by  man,  we  find 
that,  if  the  vastator  were  to  destroy  in  a  great  measure  the 
various  plants  which  it  attacks,  we  could  only  supply  the 
loss,  and  that  very  partially,  by  chestnuts,  fern  roots,  and 
bark  of  trees. 

(515.)  There  is,  however,  little  reason  to  take  so  very 
dark  a  view  of  the  case ;  there  must,  in  all  probability,  be 
some  parts  of  the  world  where  the  crops  are  good  and 
abundant,  and  whence  we  can  obtain  their  superabun- 
dance. 

(516.)  The  present  scarcity  has  been  met  with  a  supply 
of  Indian  corn  from  America,  but  it  is  possible  that  a  suffi- 
ciency of  food  might  not  exist  over  the  globe  for  the  pur- 
poses of  mankind.  And  this  year  rye  is  being  employed 
for  the  same  purpose. 

(517.)  In  such  a  case  the  council  must  endeavor  to 
provide  new  kinds  of  food.  Nutrition  may  be  obtained 
from  the  bark  of  trees,  as  in  Norway  ;  and  doubtless,  by 
care,  the  great  famines  which  before  devastated  the  world 
need  never  recur. 

(518.)  The  excise  laws  might  be  at  once  examined,  and 
the  use  of  grain  for  the  purposes  of  distillation  might  be 
prohibited,  should  any  great  dearth  be  apprehended,  as 


ON    FAMINES.  133 

spirits  could  with  equal  facility  be  made  of  sugar ;  sugar 
again  might  be  made  from  other  cheaper  materials  than 
grain,  and  by  this  substitution  alone,  a  large  quantity  of 
grain  would  be  available  for  food. 

(519.)  In  the  year  1845  scarcity  existed  throughout  all 
Europe  from  a  deficiency  in  the  potatoe  crop  ;  and  this 
year  an  even  more  alarming  failure  threatens  these  realms  ; 
so  much  so,  that  public  prayers  have  been  ordered  in  all 
the  English  churches  and  Jewish  synagogues  for  its 
abatement. 

(520.)  In  the  present  year,  1846,  from  one-half  to  two- 
thirds  of  our  potatoes  are  destroyed,  our  grain  is  short, 
perhaps  from  the  same  cause  our  vegetables  are  injured, 
our  cattle  and  sheep  are  scarce.  The  present  year  may 
be  considered  one  of  great  scarcity,  and  to  Ireland  even 
one  of  absolute  famine,  for  there  scarce  one  potatoe  exists. 
In  Devonshire  the  crop  of  potatoes  is  so  bad,  that  in  some 
places  three  men  only  raised  160  Ib.  in  a  day.  In  this 
county  potatoes  are  now  selling  at  \l.  Is.  a  bag,  whilst  the 
usual  price  is  2s.  6d.  In  Wiltshire,  I  am  informed,  that 
land  which  yielded  500  bushels  last  year,  yielded  only  50 
this  ;  and  in  Yorkshire  the  crop  is  sadly  deficient.  In 
Scotland,  I  am  told,  that  good  potatoes  are  worth  10Z.  a 
ton  ;  and  in  London,  where  the  usual  price  is  5/.  or  61.  a 
ton,  the  present  value  is  10/.  or  12Z. 

(521.)  In  estimating  the  present  famine,  we  must  not 
be  unmindful  that  we  are  at  peace  with  all  the  world,  our 
commerce  unshackled  to  procure  food  from  distant  climates. 
This  equalization  of  food  has  prevented  want ;  but,  doubt- 
less, had  it  been  otherwise,  this  would  have  been  one  of  the 
most  dreadful  famines  in  particular  localities  that  the  world 
ever  saw. 


134        ON    THE    APPLICATION    OF    DISEASED    POTATOES. 

(522.)  Even  now  we  do  not  know  whether  the  injury  is 
not  rapidly  on  its  increase,  and  what  man  can  say  that  we 
may  not  have  an  absolute  famine  next  year  ?  Under  these 
circumstances,  it  behoves  us  all  to  be  up  and  stirring  ; 
philosophers  to  investigate,  politicians  to  regulate,  the  peo- 
ple to  carry  out  their  laws :  and  having  tried  our  utmost 
to  avert  the  calamity,  to  trust  that  the  Almighty  "  may  re- 
move far  from  us  his  great  army  which  he  sent  amongst 
us,  that  our  floors  may  be  full  of  wheat,  and  that  we  may 
eat  in  plenty  and  be  satisfied."  * 


CHAPTER  XXIV. 

ON    THE    APPLICATION    OF    DISEASED    POTATOES. 

Diseased  potatoes  as  food  (523). — Thompson's  lectures :  damaged 
wheat  (524) ;  effects  of  (525) ;  difficulty  of  experimenting  on 
animals  (526).— Effects  of  mouldy  food  (527).— Probable  effects 
of  diseased  potatoes  on  man  (528 — 529)  ;  on  animals  (530 — 531) ; 
for  fattening  bullocks,  feeding  milch  cows  (532). — Used  by  bakers 
(533).— Vitiated  food  generally  (534— 535).— Starch  (536—539). 

(523.)  IT  is  difficult  to  foretell  what  may  be  the  influ- 
ence of  large  quantities  of  vitiated  vegetable  food  on  the 
human  frame.  By  cooking  we  lessen  the  deleterious  pro- 
perties of 'the  damaged  portion;  nevertheless,  having  the 
experience  of  the  baneful  effect  of  spurred  rye,  and  other 
damaged  grain,  when  used  for  food,  we  may  infer  from 

*  Joel,  chap.  ii. 


ON    THE    APPLICATION    OF    DISEASED   POTATOES.         135 

analogy  that  the  diseased  potatoe  may  in  some  cases  have 
a  similar  injurious  action. 

(524.)  I  can  refer  those  interested  in  this  subject  to 
Thompson's  Lectures  on  Inflammation,  pp.  538  to  551, 
where  the  accounts  given  by  different  writers  of  the  effect 
of  the  cockspur  rye,  or  damaged  wheat,  over  a  period  ex- 
tending from  1676  to  1762,  are  abundantly  collected. 

(525.)  The  general  effects  observed  were  mortification 
of  the  extremities,  particularly  of  the  feet.  In  most  in- 
stances the  malady  killed  the  patient,  although,  in  some 
cases,  he  survived  with  the  loss  of  the  part  affected. 

(526.)  It  is  important  to  observe,  that,  in  experiments 
made  on  animals  with  damaged  grain,  the  effect  did  not 
take  place  for  a  long  period,  and  not  then  if  the  diseased 
grain  did  not  bear  a  certain  relation  to  the  sound  food. 
From  these  facts  it  is  apparent  that  experiments,  with  the 
view  to  ascertain  the  effect  of  diseased  potatoes  on  animals, 
must  be  carried  on  for  a  long  period,  and  all  the  potatoes 
should  be  damaged.  Experiments  of  this  nature  are  sur- 
rounded by  many  practical  difficulties.  It  would  be  highly 
desirable  if  farmers  would  make  returns  of  any  injuries 
supposed  to  arise  to  animals  from  using  the  damaged  tubers. 

(527.)  Burnett  quotes  several  curious  cases  of  death 
having  arisen  from  persons  eating  mouldy  bread,  mouldy 
pork,  mouldy  cheese,  mouldy  ham  pie,  where  no  recogniz- 
able poison,  whether  mineral  or  vegetable,  could  be  traced, 
and,  indeed,  where  the  absence  of  all  known  poisons  was 
ascertained.  These  cases  are  amply  sufficient  to  warn  us 
from  eating  damaged  food. 

(528.)  Independent  of  these  extreme  effects,  we  may 
infer  that  less  severe  calamities  may  arise,  such  as  the 
London  surgeon  daily  observes  occurring  from  imperfect 


136        ON    THE    APPLICATION    OF    DISEASED    POTATOES. 

nutrition  ;  because,  although  the  potatoe  contains  the  starch 
in  a  normal  condition,  there  is  a  deficiency  in  the  nitro- 
gen ized  portion,  or,  rather,  the  nitrogenized  part,  which  is 
essential  to  the  healthy  performance  of  the  vital  functions, 
is  damaged,  and  hence  the  use  of  diseased  potatoes  is  likely 
to  give  rise  to  ulceration  of  the  cornea,  ulceration  of  the 
gums,  and  other  maladies  which  arise  from  defective  nu- 
trition? Throughout  this  year  I  have,  in  my  own  practice, 
constantly  noticed  cases  of  peculiar  ulceration  of  the 
mouth  and  gums,  but  I  have  been  unable  to  say  that  they 
were  actually  to  be  attributed  to  the  use  of  diseased 
potatoes. 

(529.)  There  is  very  little  doubt  but  that  damaged 
potatoes,  as  well  as  all  other  injured  food,  may  be  a  fruit- 
ful source  of  fever,  ulceration  of  the  bowels,  and  of  diar- 
rhoea. In  fact,  many  practitioners  have  called  attention 
to  cases  of  English  cholera  which  have  arisen  apparently 
from  this  cause. 

(530.)  The  evidence  which  I  have  endeavored  to  pro- 
cure about  their  influence  on  animals  is  contradictory.  At 
a  very  large  farm  near  London,  the  foreman  told  me  that 
he  employe  1  them  profitably  when  boiled  for  fattening 
pigs,  and  that  he  had  used  about  forty  tons  for  that  purpose. 

(531.)  At  a  farm  in  Kent,  I  heard  that  the  pigs  and 
sheep  were  killed  by  eating  diseased  potatoes,  and  that, 
therefore,  they  could  only  employ  the  potatoes  for  manure. 

(532.)  Bullocks,  I  am  told,  have  been  fattened  with 
good  success,  in  Essex,  with  damaged  tubers;  and  the 
greengrocers  inform  me  that  the  diseased  tubers  are  eager- 
ly bought  by  the  cow-keepers,  as  they  are  found  to  cause 
the  animal  to  give  abundance  of  milk. 

Against  this  application  I  strongly  protest,  for  the  sup- 


ON   THE    APPLICATION    OF    DISEASED    POTATOES.        137 

ply  of  wholesome  milk  is  of  great  importance  to  the  com- 
munity  ;  and  I  hope  a  law  will  be  enacted  to  prevent  this 
disgraceful  practice  from  being  continued. 

(533.)  The  bakers  also  are  not  very  particular  about 
the  state  of  the  potatoes  which  they  employ.  Price,  not 
quality,  is  their  motto  ;  and  though  they  prefer  the  pota- 
toes when  sound,  they  do  not  particularly  object  to  their 
being  partially  rotten.  It  is  quite  surprising  to  me  that 
the  present  extensive  adulteration  of  bread  with  alum 
should  be  allowed  to  exist  for  a  single  day  ;  and  whilst  the 
bakers  are  allowed  constantly  to  employ  alum,  I  do  not  see 
why  they  should  not  also  use  vitiated  potatoes,  or  any 
other  noxious  ingredient  of  which  they  can  make  a  profit- 
able use. 

(534.)  Notwithstanding  the  partial  indemnity  which 
appears  to  attend  the  use  of  damaged  potatoes,  I  must  ex- 
press a  strong  conviction  that  the  use  of  vitiated  food  of  any 
kind  is  liable  to  give  rise  to  disastrous  results. 

(535.)  We  are  not  only  employing  vitiated  potatoes, 
but  we  are  employing  likewise  milk  produced  from  the 
same  material,  and  from  even  worse  material  ;  for  the 
cows  are  fed  likewise  on  diseased  beet  and  turnips. 

Under  these  circumstances,  disease  and  excessive  mor- 
tality may  be  expected  •  for  we  may  be  influenced  by 
diseased  food  through  our  milk  and  bread  at  breakfast ; 
we  may  then  have  damaged  vegetables  at  dinner,  and 
return  to  damaged  food  for  tea. 

(536.)  There  can,  however,  be  no  possible  objection  to 
the  separation  of  the  good  matter  from  the  bad,  and  I  have 
already  pointed  out  that  the  starch  is  left  nearly  entire. 
This  process  has  already  been  described,  and  the  separated 
starch  may  be  kept  and  stored  up  for  future  use. 


138          BENEFITS   AND   DANGERS   OF   THE    POTATOE. 

(537.)  When  extracted,  the  starch  may  be  employed 
for  fattening  cattle,  when  mixed  with  other  substances ; 
and,  indeed,  may  be  used  for  human  food,  when  associated 
with  skim-milk  or  cheese,  to  supply  the  deficient  nitrogen- 
ized  portions.  The  starch  from  the  most  offensive  potatoe 
will  make  good  puddings,  or  it  may  be  mixed  with  flour 
for  bread. 

(538.)  This  starch  might  also  be  converted  into  dextrine 
for  the  purposes  of  the  arts,  and  might  be  made  into  sugar 
for  the  production  of  spirits. 

(539.)  Upon  the  whole  it  is  most  desirable  that  the 
starch  should  be  extracted  from  the  diseased  tubers,  and 
used  for  the  purposes  of  the  arts,  where  it  could  not  possi- 
bly commit  any  damage ;  whereas  the  use  of  diseased 
potatoes  for  human  food,  for  bread,  or  for  milch  cows, 
should  be  strictly  forbidden. 


CHAPTER  XXV. 

THE    BENEFITS    AND    THE    DANGERS    OF    THE    POTATOfi. 

Value  of  the  potatoe  (540).— Culture  (541)-— Nutritive  power  (542, 
543). — Exclusive  potatoe  culture,  moral  effects  (544);  physical 
effects,  the  Irish  (546,  547).— Dangers  of  (548). 

(540.)  THE  potatoe  plant  affords,  for  the  labor  and  space 
required  for  its  cultivation,  more  alimentary  matter  than 
any  other  plant  whatever,  and  on  that  account  is  a  valu- 
able source  of  food  for  mankind. 

(541.)  Cottagers  have  but  to  dig  the  ground,  plant  the 


BENEFITS   AND   DANGERS    OF    THE    POTATOE.  139 

potatoes,  earth  them  up,  and  gather  them  in,  when  they  are 
at  once  ready  for  culinary  purposes,  without  the  aid  of 
mills,  machinery,  or  other  preparation. 

(542.)  The  plant,  moreover,  is  competent  of  itself  to 
supply  every  requisite  for  nutrition.  It  yields  carbon  for 
the  lungs,  nitrogen  for  the  muscles,  phosphorus  and  iron 
for  the  blood,  lime  for  the  bones,  and  in  fact  a  human  be- 
ing might  live  upon  potatoes  alone. 

(543.)  In  practice,  every  man  with  an  acre  of  land 
can,  by  means  of  the  potatoe,  support  himself  and  family ; 
and,  instead  of  requiring  anything  from  without,  may  live 
independently  and  careless  of  all  surrounding  creatures 
and  objects. 

(544.)  As  a  consequence  of  this,  a  nation  of  potatoe- 
eaters  does  not  feel  those  relations  and  dependenbies  which 
bind  other  societies  together.  A  man's  own  labor  sup- 
plies him  with  food,  and  he  cares  not  for  nor  requires  any 
other  man's  assistance  ;  hence,  many  of  the  social  relations 
are  destroyed  ;  the  relation  between  the  laborer  and  the 
farmer,  the  miller  and  the  baker,  do  not  exist ;  and,  in  the 
end,  each  man  is  in  his  own  person  king,  magistrate,  and 
subject,  not  caring  for  the  assistance  nor  fearing  the  dis- 
pleasure of  any  other  human  being. 

(545.)  Nature  has,  however,  put  a  barrier  to  the  exten- 
sion of  this  unsocial  condition;  for  the  potatoe  can  be  pre- 
served only  one  year,  and  a  break  in  the  continuity  of  the 
potatoe  would  at  once,  if  the  above  state  of  things  existed, 
restore  the  social  relations. 

(546.)  This  effect  of  depending  too  exclusively  on  the 
culture  of  the  potatoe  is  fearfully  exhibited  in  the  Irish 
people,  where  the  potatoe  has  begotten  millions  of  paupers, 
who  live,  but  who  are  not  clothed ;  who  marry,  but  do  not 


140  RESUME. 

work,  caring  for  nothing  but  their  dish  of  potatoes.  If  left 
to  itself,  this  fearful  state  of  things  would  have  remedied 
itself;  for,  had  the  people  the  control  of  their  own  commu- 
nity, and  had  the  potatoe  crop  failed  to  the  extent  to  which 
it  has  this  year,  these  people,  having  no  relation  with  any 
other,  would  have  been  left  to  their  own  resources,  which, 
being  destroyed,  would  have  left  them  without  food. 

(547.)  Millions  of  human  beings,  desperate  with  hunger 
and  untutored  in  laws,  would  have  devastated  the  country  ; 
this  would  have  aggravated  the  misery,  and  at  last  numbers 
would  have  perished  of  starvation,  and  the  mutual  relations 
of  the  survivors  would  have  been  re-established.  Fortu- 
nately for  the  Irish  people,  they  have  a  rich  and  powerful 
country  to  sympathize  with  and  relieve  them  in  their  dis- 
tress, and  also  desirous  of  alleviating  their  suffering. 

(548.)  A  lesson  is  here  taught  to  mankind,  to  lay  up 
stores  against  the  day  of  scarcity,  and  not  to  trust  to  so 
uncertain  a  thing  as  a  crop  of  potatoes  for  subsistence,  but 
always  to  cultivate  a  sufficiency  of  grain  to  be  stored  up 
and  preserved  against  a  time  of  scarcity  and  famine. 

We  thus  find  that  the  potatoe,  from  its  containing  every 
element  of  nutrition,  is  a  valuable  food,  and  to  be  freely 
cultivated,  though  considerable  mischief  may  arise  from 
excessive  and  improper  planting. 


RESUME. 
(1.)  A  POTATOE  plant  consists  of  a  root  to  take  up  water. 


RESUME.  141 

leaf  to  deposit  solid  matter,  and  a  stem  with  its  tuber  to 
supply  nutrition. 

(2.)  The  potatoe  plant,  as  we  cultivate  it,  is  in  a  diseased 
or  abnormal  condition,  having  great  excess  of  tuber  and  great 
deficiency  of  leaves. 

(3.)  The  potatoe  is  employed  chiefly  on  account  of  its 
starch  and  albumen,  parts  which  it  derives  from  the  leaf. 

(4.)  The  plant  is  subject  to  death  at  various  parts,  or  a 
sort  of  vegetable  gangrene. 

(5.)  This  death,  m  the  form  presented  by  the  present 
disease,  is  influenced,  but  not  caused,  by  heat,  light,  elec- 
tricity, moisture,  soils,  and  manures. 

(6.)  It  is,  however,  caused  by  the  Aphis  vastator,  which 
punctures  the  leaf,  sucks  the  sap,  and  destroys  the  relation 
between  the  leaf  and  the  root,  thus  causing  the  leaf  or  some 
other  part  of  the  plant  to  become  gangrenous,  or,  in  other 
words,  to  die. 

(7.)  The  vastator  destroys,  in  the  same  manner,  the 
turnip,  the  Swede,  the  beet-root,  the  cabbage,  the  brocoli, 
the  radish,  the  horse-radish,  the  various  wild  solani,  some 
kinds  of  henbane,  the  stramonium,  the  belladonna,  the 
clover,  the  groundsel,  the  euphorbia,  some  sorts  of  rumex, 
the  mallow,  the  shepherd's  purse,  the  holy  thistle,  some 
kinds  of  grass,  and  will  live  upon  wheat,  the  Jerusalem 
artichoke,  the  sweet  potatoe,  and  doubtless  many  other 
plants. 

(8.)  After  the  attack  of  the  vastator  fungi  grow,  which 
growth  is  probably  in  many  cases  materially  assisted  by 
the  prior  attack  of  the  Aphis. 

(9.)  Other  kinds  of  Aphides  will  kill  in  the  same  man- 
ner apple-trees,  the  hop,  the  bean,  the  pea,  the  wheat,  the 


142  RESUME. 

oat,  various  grasses,  geraniums,  the  rose,  the  larch,  and 
doubtless  many  other  plants. 

(10.)  The  excessive  appearance  of  any  particular  insect 
is  no  new  fact,  but  has  been  before  noticed  in  the  locust, 
various  caterpillars,  the  cockchafer,  and  in  many  other 
instances. 

(11.)  The  excessive  increase  of  one  species  of  Aphis  is 
generally  attended  with  a  corresponding  increase  in  other 
species,  so  that  human  food  may  be  attacked  at  all  points. 

(12.)  Aphides  are  kept  in  subjection  by  ichneumons  and 
other  Hymenoptera  ;  by  various  Coleoptera,  as  lady-birds  ; 
by  some  dipterous  insects,  and  by  spiders,  birds,  &c. 

(13.)  According  to  analogy  the  disease  is  doubtless 
transitory,  and  will  pass  over  the  globe  and  disappear.  It 
may,  however,  yet  increase^  and  kill  millions  from  famine 
before  it  finally  departs. 

(14.)  A  diseased  potatoe  may  grow  a  diseased  potatoe, 
and  thus  propagate  the  malady ;  although  it  is  also  pretty 
certain,  that  a  rotten  potatoe,  under  certain  circumstances, 
may  grow  a  sound  one. 

(15.)  We  do  not  observe  the  effects  of  the  disease  to  such 
an  extent  in  those  plants  which  we  employ  before  they  are 
required  to  develope  their  fibre,  and  therefore  before  they 
exhibit  the  gangrene  to  any  very  great  extent. 

(16.)  The  disease  may  probably  be  lessened  by  striking 
at  the  cause,  and  destroying  the  Aphis  to  as  great  an  extent 
as  possible — by  employing  birds  for  that  purpose,  by  burn- 
ing infected  haulms,  and  isolating  from  each  other  all  plants 
liable  to  be  affected  by  the  insect. 

(17.)  A  diseased  plant  may  possibly  be  rendered  less 
liable  in  future  to  the  disease,  by  causing  it  for  some  time 
to  revert  as  much  as  possible  to  the  wild  state,  which  is  to  be 


RESUME.  MS 

effected  by  growing  it  in  dry  places,  from  a  shoot  or  cutting 
of  the  stem,  or  small  piece  of  sound  potatoe,  by  applying  to  it 
but  little  manure,  plenty  of  light,  and  selecting  a  sandy  or 
peaty  soil,  and  warm  situation,  the  object  being  to  obtain  a 
sufficiency  of  leaves  to  develope  fibre,  and  to  repress  over- 
abundant and  very  rapid  growth. 

(18.)  Above  all  things  we  should  take  care,  as  far  as 
possible,  that  the  fibre  is  deposited  in  the  plant  at  a  period 
of  the  year  before  the  insect  becomes  very  abundant. 

(19.)  The  potatoe  plant  is  a  plant  of  indolence,  and 
politically  injurious  to  the  community  when  extensively 
employed,  and  the  excessive  cultivation  of  this  esculent 
may  cause  alarming  famines. 

It  has  great  advantages,  however,  from  the  quantity  of 
nourishment  which  may  be  raised  in  a  given  space,  and 
because  it  affords  every  material  requisite  for  nutrition. 


145 


APPENDIX. 


I. 

I  SHOULD  feel  extremely  obliged  if  agriculturists  in  all 
parts  of  England  would  transmit  to  me  the  following  returns 
connected  with  the  disease  of  potatoes,  whenever  they  have 
the  opportunity  of  procuring  them. 


Kind  of 
Potatoe. 

When 
Planted.     - 

Nature  of 
Soil. 

What  Manure 
used. 

Total 
Produce. 

Quantity  of 
Good. 

Quantity  of 
Bad. 

Month  in  which 
disease  appeared. 

(2.)  With  respect  to  the  insect,  I  should  also  be  glad  if  they  would 
transmit  to  me  frequent  returns  as  to  its  numbers,  and  the  plants 
it  infests.  In  all  cases  where  other  plants,  besides  those  already 
mentioned,  are  attacked,  I  should  be  glad  if  they  would  transm  i 
a  few  of  the  insects  in  a  pill-box,  cut  down  so  as  to  be  nearly  flat 
for  inclosure  in  a  note.  Whenever  the  destroying  cloud  appears, 
I  should  like  to  have  immediate  notice. 
7 


146  APPENDIX. 

(3.)  As  far  as  regards  the  destroyers  of  the  insect,  I  should  be  glad 
also  to  be  constantly  informed  of  the  progress  of  the  lady-birds 
and  ichneumons  ;  and  also,  when  the  insects  greatly  abound,  to 
have  accounts  transmitted  of  the  actual  number  of  insects  con- 
tained in  the  crops  of  various  birds. 

(4.)  I  should  like  also  to  know  whenever  mischief  appears  to  arise 
from  the  use  of  damaged  potatoes  by  cattle  or  by  man. 

(5.)  Should  any  other  Aphis  appear  in  any  quantity,  I  should  be 
pleased  to  receive  specimens,  as  one  Aphis  in  excess  is  apt  also 
to  be  attended  with  a  larger  development  of  other  Aphides 

(6.)  If  by  any  chance  this  work  should  fall  into  the  hands  of 
foreigners,  I  should  also  feel  under  great  obligations  if  they  would 
favor  me  with  similar  returns. 

If  these  returns  are  made  to  a  considerable  extent  from  all  counties 
of  England,  and  I  should  not  lose  as  much  money  by  the  publica- 
tion of  this  work  as  usually  happens  to  the  lot  of  scientific  writers, 
I  propose  to  make  this  Treatise  expansive,  by  publishing  con- 
tinual Supplements,  as  occasion  may  require.  The  above  tabular 
return  is  wanted  directly ;  and,  therefore,  I  solicit  newspapers 
and  magazines,  the  present  great  organs  of  knowledge,  to  copy  it, 
that  it  may  be  immediately  prepared. 

In  case  these  returns  should  be  sent  in  any  great  num. 
bers,  I  beg  that  the  letters  may  be  endorsed  on  the  enve- 
lope, "  Public,"  that  I  may  open  them  at  my  conveni- 
ence. 

It  has  happened  on  former  occasions  that  I  have  been 
unable  to  answer  the  various  questions  upon  public  sub- 
jects submitted  to  me,  from  my  time  being  occupied  with 
subjects  which  absolutely  demand  my  prior  attention.  For 
all  these  omissions  I  hope  the  writers  will  excuse  me,  as, 
whenever  my  occupation  would  permit,  I  have  rendered 
the  information  required  to  the  best  of  my  power. 


147 


APPENDIX   II. 


List  of  One  Hundred  and  Sixty  Kinds  of  Potatoes  obtained  from 
the  Gardens  of  the  Horticultural  Society,  with  the  Weight  of 
each  Tuber  and  the  Sp.  Grav.,  which  will  roughly  indicate  the 
Quantity  of  Solid  Material ,  and  consequently  the  value  of  each 
kind. 


Kind  and  Color. 

Canada  pine,  white 

La  Bernard,  red 

La  Canterbury,  white 

Durham,  or  mossy,  white 

Les  Orphelines,  white 

Quarry,  or  low  lines,  white    . 

American  Native,  white 

Vaughan's  Seedling,  white     . 

Black's  (la  noir  gros)  > 

Purple  Kidney 

Yorkshire  Red 

Juane  Tardive,  white 

Long  Red  Kidney 

Carnichon  jaune,  dit  la  Parmentier,  white 

Bellows  Nose,  white  . 

Smooth  Red  Kidney    . 

Ormeskirkes,  white     . 

Maisbury  Red 

White  Kidney 

La  feuille  de  Haricot,  white  . 

White  .... 

Bullock's  Heart,  white 

The  Honor  of  Westwald,  pink 

Blue  Red  Marbled,  brown 

Black  Kidney,  deep  purple     . 

La  Baviere,  white 

Cornish  Kidney,  white 

La  Jaune  Seine  Longue,  brown 


Weight 
of  Tuber. 

Sp.  Gr. 

1374 

1-068 

673'i 

1-090 

754.1 

1-097 

1057 

1-094 

1190 

1-103 

1425-1 

1-071 

10981 

1-073 

850'Q 

1009 

1010 

1  044 

5      744-1 

1-067 

805-4 

1-058 

1675-4 

1-099 

582-9 

1-069 

1787-5 

1-110 

1582 

1-U88 

1526  1 

1-083 

1084-5 

1-079 

223-75 

1-075 

1066 

1-077 

555 

1-094 

118S 

1-116 

1186 

1-088 

1043 

1-078 

523 

1-094 

1390 

1-095 

1517 

1-090 

1278-5 

1-077 

659-5 

1-090 

148 


APPENDIX  II. 


Kind  and  Color. 

Early  Champion,  brownish  white      . 

Farmer's  Seedling,        do. 

Hative  de  Mendon,  purple     . 

Jaune  Blanche,  brown 

Le  bon  Pommir,  red  spotted  . 

La  souries  jaune,  white 

La  Beaulien  Marbree,  purple 

Chapman's  New  Spring  Kidney,  white 

English  Khynsburgh,  brown  . 

La  Bleu  de  Forets,  red 

Walton  Hall,  yellow  . 

La  Jaune  Haricot,  brown 

Lanckman's  Red,  pink 

Early  Walnut-leaved,  brown  . 

Brown's  Potatoe,  white 

White-eyed  Red 

La  Chionese,  ou  Sucree,  white 

Spanish,  white 

Jaune  Hative,  brown 

La  Coton,  pink 

Champion,  white 

Cruikshank's  Early,  white 
Large  Yellow 

Raith,  white    . 
La  Batave,  white 

Shaw,  white    .  ,,^  .'  j' 

•White  Oporto,  white  . 
Downton  Yam,  pink   . 
Devonshire  Red 
Knight's  Seedling,  1,  brown  . 
July,  white      .... 
Everlasting,  pink 
Philadelphia,  brown    . 
Knight's  Seedling,  2,  purple 
Lady's  Finger,  purple 
Leather  Coat,  white    . 
Burrowe's  Early  white 
New  Potatoe,  white    . 
Hotteshe's  Potatoe,  light  red 
Vitelotte,  pinkish        .        />•'•"        -.'.. 
Large  Cattle,  white    .  / 

Early  Dwarf,  pink 
Dwarf,  white 
Petit  Jaune,  white 
Angleterre  Hative,  white 
Goldfinch,  white 


Weight 
of  Tuber. 

Sp.  Gr. 

1117-5 

1087 

771 

1-086 

1066-5 

1-044 

1895 

1-010 

996 

1-086 

650 

1-092 

504-5 

1-086 

1500 

1-080 

1190 

1-082 

1057 

1-082 

558 

1-084 

1285-5 

1-087 

1418  ' 

1-084 

780-05 

1-091 

719-5 

1-090 

1128-1 

1-098 

841 

1  100 

872-5 

1-082 

777 

1090 

603 

1  079 

1207 

1-099 

1079-5 

1-084 

1092  5 

1096 

1389 

1-092 

870 

1-082 

2039-5 

1-099 

1014 

1  095 

1819 

1-081 

840 

1-097 

600-5 

1-086 

1146 

1-079 

1074-5 

1-067 

1203 

1  098 

1025 

1-083 

313 

1-078 

883 

1-078 

1342-4 

1-072 

901-6 

1  077 

699-9 

1-079 

996-5 

1-076 

1319-5 

1-056 

516-5 

1-086 

859-5 

1-083 

672-5 

1-077 

1161 

1-088 

613 

1-085 

APPENDIX  H. 


149 


Kind  and  Color. 

Seedling  White 

Oxnoble,  white 

Hog's  Goliah,  light  purple 

South  American,  white  .-„ 

Early  purple  marbled 

New  Swiss  Kidney,  light  purple 

Bermuda,  No.  2,  white 

Robertson's,  white 

La  Semi  Rouge,  pale  pink  -.  -.'.' 

La  Longbrin,  pale  pink 

Pink  (Oporto),     do. 

Large  Pale  Red,  do.    .  v. 

Large  white,        do.    . 

Lancashire  Red 

Ormeskirkes  Early  Dwarf,  white 

Oxnoble  ?,  white 

Bermuda  No.  1 ,  red  spotted  . 

Large  July,  white 

Yellow  .  .         .;  i  ,• 

La  Prime  Rouge,  pink 

La  Oxnoble,  white 

Jersey  Blue,  purple    . 

Pink  Kidney   . 

Red  Kidney     . 

La  Rose  Oeil,  white    .        ,    . 

La  Rose  Jaune,  pink  .          •  * 

Bangor  Rouge,  red 

Violet  de  M.  Sagaret,  reddish  whit* 

Biscuit,  red  spotted     .  . 

Potatoe  Pannels,  white  „ 

Ash-leaf  Kidney,  white  ,.' 

Yorkshire,  white         .        :    .. 

Latige  Couche,  white  .. 

Sweeney  Seedling,  red 

Bread-fruit,  white 

Long  Faint  Red 

Potatoe  from  Hamburgh,  white 

Golden  Knob,  yellow  . 

Round  Black,  nearly  black 

La  Truffe  d'Aout,  red 

Hative  de  Juin,  white  „ 

Holland  Jaune,  white 

Housekeeper's  Delight,  white 

Rouge  Pale,  white       .        ;'  ..  " 

La  Blanche  Longue,  white     . 

Mule,  brownish 


Weight 
of  Tuber. 

Sp.  Gr. 

1349-25 

l'094i 

860 

1-108 

1015-5 

1  079 

1155-5 

1-087 

979-5 

1-083 

965-25 

1-083 

2688 

1-064 

437-75 

1-093 

425-25 

1-089 

735-25 

1-079 

1832  5 

1-082 

850-25 

1-067 

1097-5 

1-082 

1028 

1-086 

1132-5 

1-085 

1704-5 

1-062 

1099-5 

1  067 

3018 

1-084 

809-3 

1-084 

5073 

1090 

1163 

1-095 

906-4 

1-084 

825-5 

1-082 

761-8 

1-091 

439-8 

1-105 

409-5 

1-078 

1067-3 

1-089 

428-4 

1-097 

534 

1-058 

956-2 

1-077 

1363-1 

1-074 

1131-4 

1-103 

1953-4 

1-081 

566-5 

1-080 

926 

1-096 

1078 

1  081 

1326-1 

1  095 

1844 

1-086 

1182-1 

1-079 

800-8 

1-100 

2399-5 

1-089 

892 

1-106 

1030 

1-084 

548-1 

1-070 

519-2 

1-061 

1083 

1-093 

150 


APPENDIX  II. 


Kind  and  Color. 

Bonne  Bellot,  red        .. 

Early  Shaw,  white 

Dutch,  white  . 

Winchfield,  light  pink  >, 

La  Jeanette,  white      .  .-       •  .  .'; 

La  Degeneree,  pink    .  .  -*/{ u 

Gloucestershire  Pink  .  . 

Flat  White,  yellow     . 

Ouion,  brown  .... 

Neapolitan,  white 

Knight's  No.  6,  pinkish  white 

La  Guerine,  brown 

Early  bright  Red  Palatinate,  white    . 

Early  Kidney,  pink     . 

New  Grenada,  white  .  .          •>"• 

Black  la  Violette,  pale  pink   . 

La  Jaune  Cylindricei  . 

Azores,  pink    .... 

Large  Yellow,  La  Grosse  Irlandoise,  white 

Carnichon  Rouge  de  Holland,  pink    . 

Grosse  Jaune,  white   . 

Violette  a  Chaire  Marbree,  pink 

New  Hundredfold,  white 

La  Patagne,  pink 

Cambridge,  white 

Albion,  white  .... 

Knight's  Yellow  Kidney 

Rossshire,  white  .  .        '  'w-.dt.i 

Belle  Ochreuse,  pink  . 

Round  Red  German,  deep  purple 

Early  Manly,  yellow  . 

Johnstone's  Pink         .  •>    . 

Early  Kidney,  white    .  -.„ 

Hollande,  pink  .. 

Everlasting,  pink        ...          .».          •». 

Golden,  white         .-"*,.  .,  , 

Mageniaise,  pink 

La  Claire  Bonne,  red  .          ;'*?  . 

Girkin,  brown  .. 

Pink-eyed        .... 

Chelsea  Wild,  white  and  red 


Weight 
of  Tuber. 

Sp.  Gr. 

830-4 

1-094 

1247-6 

1-069 

1522-5 

1-078 

664-2 

1-088 

10691 

1.0S3 

447-1 

1-095 

744 

1  -092 

811 

1-093 

1123 

1-092 

995 

1-087 

1206-5 

1-052 

1074 

1-089 

553 

1-090 

914 

1-076 

714-5 

1-085 

418 

1-086 

481 

1083 

803 

1-086 

531 

1-011 

756 

1-069 

756 

1084 

588 

1-152 

465 

1-086 

720 

1-100 

663 

1-067 

794 

1-076 

904 

1-OS4 

1056 

1-086 

444 

1-085 

574 

1-086 

622 

1-089 

557 

1-096 

1434 

1-078 

273 

1079 

928 

1-074 

995 

1-089 

846 

1-101 

1031 

1-095 

890 

1-092 

449 

1-080 

1395-5 

1-085 

1)1 


INDEX. 


ACARUS  found  on  the  potatoe  plant,  61;  found  in  company  with 

Aphis  vastator,  106. 

Albumen,  its  probable  source,  4;  prob.ible  composition,  19;  in  a 
state  of  putrefaction  in  diseased  tubers,  40  ;  converted  into  vege- 
table casein,  ib. 

Alcohol  made  from  potatoes,  25 
Alimentary  substances,  list  of,   131 ;  number  of,  attacked  by  the 

vastator,  ib. 

Analysis  of  potatoe  plant,  17;  of  potatoe,  18;  of  solanine,  ib. ;  of 
diseased  potatoes,  40 ;  of  potatoes  in  various  years,  ib. ;  mode  of, 
33  ;  ultimate  of  potatoe,  19  ;  of  dextrine,  25. 
Aphides,  importance  of  the  family  of,  91-94. 

Aphis  of  the  hop,  91  ;  of  the  cabbage  and  turnip  (A.  brassicae),  92  ; 
abundance  of,  102  ;  of  the  pea,  92  ;  of  the  bean,  ib.;  lanigeri,  ib.; 
of  the  sycamore,  93  ;  of  the  sugar-cane,  ib.;  on  the  larch,  ib.;  on 
the  rose,  94  ;  on  the  couch-grass,  ib. ;  excessive  numbers  seen  in 
various  places,  96  ;  analogy  of  various  species  of,  101 ;  relation  of, 
to  fungi,  102;  causes  of  excess  of,  ib  ;  natural  remedies  for,  103- 
103  ;  artificial  remedies  for,  118-127;  difficulty  of  destroying, 
119. 

Aphis  vastator,  importance  of,  62  ;  not  found  alone,  63  ;  description 
of,  ib.;  states  in  which  it  is  found,  64 ;  size  and  color  of,  ib.; 
measurement  of,  65  ;  mode  of  preserving  for  examination,  xxxv.  ; 
identity  of,  with  A.  rapae,  ib.;  reasons  for  its  name,  ib.;  generation 
of,  6S  ;  fecundity  of,  66  ;  questions  respecting  generation  of,  ib. ; 
attacks  the  potatoe  plant,  69-71  ;  unpleasant  sensation  caused  by, 
70  ;  widely  diffused,  71  ;  migratory  habits  of,  ib. ;  does  not  attack 
all  potatoes  alike,  ib. ;  scarcely  affects  wild  potatoes,  ib. ;  damages 
plants  in  ratio  with  their  growth,  72;  attacks  various  plants,  73, 
141 ;  turnip  attacked  by,  74,  78  ;  appears  to  prefer  the  turnip  to 
the  potatoe,  78  ;  beet  and  mangel-wurzel  attacked  by,  79  ;  spinach 
attacked  by,  81  ;  carrots  attacked  by,  ib. ;  identity  of  effects  pro- 
duced by,  82  ;  seems  to  have  a  preference  for  the  Solanseae,  84 ; 
found  on  Solanum  dulcamara,  83  ;  S.  nigrum,  ib. ;  Atropa  bella- 
donna, 84  ;  hyoscyamus,  ib. ;  stramonium,  ib. ;  attacks  Cruciferae 
next  to  Solanaeae,  85;  found  on  cabbage  and  brocoli,  ib. ;  horse- 
radish, ib.;  tomato,  86;  Indian  corn,  ib. ;  wheat,  ib. ;  not  to  be 


152  INDEX. 

confounded  with  another  Aphis  on  wheat,  86  ;  did  not  appear  till 
August,  87  ;  does  not  live  on  the  oat,  ib. ;  found  on  other  grasses, 
ib. ;  Jerusalem  artichoke,  &8  ;  the  nettle,  ib. ;  the  mallow,  ib. ; 
heart's-ease,  ib.  ;  Coreopsis  tinctt<ria,  ib. ;  the  parsnip,  89  ;  chick- 
weed,  ib.  ;  elder,  ib.  ;  Geranium  molle,  ib. ;  the  plantain,  ib. ; 
groundsel,  ib.  ;  shepherd's  purse,  ib. ;  spurge,  ib.  ;  marigold,  90; 
peach,  ib. ;  celery,  ib. ;  Convolvulus  battata,  ib  ;  excessive  ap- 
pearance of,  an  instance  of  loss  of  balance  in  nature,  95,  96 ;  re- 
medies for,  103,119;  reason  for  its  attacking  old  leaves,  113; 
changes  its  state  when  the  plant  is  killed,  114  ;  not  destroyed  by 
rain,  119;  artificial  remedies  for:  removal  of  diseased  leaves, 
120 — quicklime,  ib. ;  importance  of  the  period  of  its  appearance, 
121. 

Apple-trees  affected  by  Aphis  lanigera,92;  crops  of,  almost  de- 
stroyed. 93  ;  progress  of  A.  lanigera,  ib. 

Autumn  planting,  121. 

Bean  plants  attacked  by  an  Aphis,  92,  131. 

Beet  attacked  by  the  Aphis  vastator,  79  ;  mode  and  progress  of  the 
attack,  80  ;  suffers  most  when  running  to  seed,  ib.  ;  number  of 
Aphides  on  one  plant,  xxxii.,  80. 

Belladonna  attacked  by  Aphis  vastator,  84. 

Berkeley,  Mr.,  opinion  respecting  the  potatoe  disease,  55,  56. 

Bostrichus  typographus  destructive  to  firs  in  certain  years,  98. 

Botrytis  infestans,  57  ;  figured  by  Mr.  Berkeley,  ib. 

Boussingault  and  BaBchmann,  ultimate  analysis  of  potatoe  by,  68. 

Bread  made  from  potatoes,  23  ;  adulteration  of,  with  potatoes,  ib.  ; 
with  diseased  potatoes,  137;  with  alum,  ib. 

Brown-tail  moth,  vast  numbers  of,  in  1782,  98. 

Butyric  acid  found  in  rotten  potatoes,  41. 

Cabbage  attacked  by  the  Aphis  vastator,  85. 

Carrot  attacked  by  Aphis  vastator,  81  ;  mode  of  attack,  ib. ;  most 
liable  to  attack  when  running  to  seed,  82. 

Celery  attacked  by  the  Aphis  vastator,  90. 

Chama,  27. 

Chickweed  attacked  by  Aphis  vastator,  89. 

Chrysopa  perla  destroys  Aphides,  J04. 

Cockchafers,  immense  number  of,  97  ;  grub  of,  very  destructive,  ib. 

Commissioners  to  investigate  the  potatoe  disease,  xxix. 

Convolvulus  battata  in  use  before  the  potatoe,  15;  cultivated  by 
Gerard,  16  ;  modern  attempts  to  naturalize,  ib.  ;  attacked  by  the 
Aphis  vastator,  90. 

Coreopsis  tinctoria  attacked  by  the  Aphis  vastator,  88. 

Couch-grass  attacked  by  the  Aphis  vastator,  94. 

Council  of  health  proposed,  129 

CruciferaB  very  liable  to  the  attack  of  the  Aphis  vastator,  85. 

Curl,  description  of,  108,  109. 

Curtis,  description  of  Aphis  rapas  by,  67. 


INDEX. 


153 


Dextrine  made  from  potatoe  starch,  25  ;  composition  of,  ib. ;  used 
to  gum  postage  stamps,  ib. 

Diseased  vegetables,  effects  of,  on  animals,  135;  effects  of  often  de- 
ferred, ib. ;  effects  of  cooking  on,  134. 

Diseased  food,  instances  of  death  from,  135  ;  must  be  deleterious, 
136. 

Diseased  potatoes,  purposes  for  which  they  are  employed,  137  ;  con- 
sequences of  their  use,  136,  137;  English  cholera,  136. 

Distillation  from  potatoes,  25  ;  why  abandoned,  26  ;  from  grain, 
question  of  prohibition  of,  132. 

Distribution  of  the  potatoe  plant,  27. 

Early  varieties  of  potatoe  less  liable  to  the  disease,  46. 

Earwing,  probably  a  destroyer  of  Aphides,  106. 

Elder  trees  attacked  by  the  Aphis  vastator,  89. 

Electricity,  effects  of,  on  plants,  50. 

Endosmose  may  explain  the  motion  of  sap,  5. 

Enumeration  of  plants  attacked  by  the  Aphis  vastator,  141. 

Eriosoma.     See  Aphis  lanigera. 
•   Eupteryx  solani  not  the  cause  of  the  potatee  disease,  62. 

Evelyn's  account  of  the  potatoe,  20. 

Exhalation  of  water  from  potatoe  plants,  immense,  5. 

Famines,  frequency  of,  informer  times,  128;  enumeration  of,  ib. ; 
prevention  ot,  by  Governments,  129  ;  question  of,  next  year,  134. 

Fibre  deficient  in  diseased  plants,  124;  probable  means  of  obtaining 
development  of,  125 ;  importance  of  early  development  of,  143. 

Fir  trees  destroyed  by  an  insect,  100. 

Frost,  action  of,  on  potatoes,  26. 

Frosted  potatoes  used  for  distillation,  26. 

Fungi,  prevalence  of,  on  decaying  matter,  56  ;  question  of  origin  of, 
ib. ;  various  kinds  of,  ib. ;  supposed  to  be  the  cause  of  the  disease, 
55;  species  found  on  potatoes,  56,  57;  motion  observed  in,  59  ; 
influence  of,  on  the  disease,  ib. ;  use  of,  in  removing  decaying 
matter,  60  ;  may  render  the  potatoe  poisonous,  ib. ;  attack  the 
turnip  after  the  Aphis  vastator,  76;  relation  of,  to  the  injuries 
caused  by  the  family  of  Aphides,  102,  141. 

Gangrene  of  the  potatoe  plant.  See  potatoe,  disease  of.  Sicca,  or 
dry,  28  ;  humida';  or  moist,  ib. ;  mode  and  progress  of  the  attack, 
29,  34. 

Geranium  molle  attacked  by  the  Aphis  vastator,  89. 

Gerard's  description  of  the  potatoe  plant,  8, 19. 

Gluten  in  a  state  of  putrefaction  in  diseased  tubers,  40,  42. 

Government,  duty  of,  in  a  time  of  scarcity,  130. 

Greatrex,  Mr.,  his  account  of  the  disease,  45. 

Groundsel  attacked  by  the  Aphis  vastator,  89. 

Guano,  its  influence  on  the  disease,  54 ;  its  effects  on  other  plants,  ib. 

Haulrn,  3  ;  result  of  cutting  when  diseased,  36,  122  ;  if  diseased, 
should  be  burnt  when  the  crop  is  gathered,  ib. 

Hollin's  description  of  curl,  108. 


154  INDEX. 

Hop  crop  often  nearly  destroyed  by  an  Aphis,  91 . 

Horseradish  attacked  by  the  Aphis  vastator,  85. 

Humboldt  denies  the  existence  of  wild  potatoes  in  Peru  and  the 
Andes,  9,  10. 

Hyoscyamus  attacked  by  the  Aphis  vastator,  84. 

Hypogymna  dispar,  effects  of,  on  oaks,  98. 

Ichneumons  destroy  Aphides,  105. 

Indian  corn  attacked  by  the  Aphis  vastator,  86  ;  a  substitute  for  the 
potatoe,  132. 

Information  desired,  145  ;  form  for  collecting,  ib. 

Insects  found  on  the  potatoe  plant,  61  ;  plagues  of  the  Old  Testa- 
ment, 96 ;  excessive  appearances  of,  97-100  ;  no  new  fact,  142  ; 
kept  within  bounds  by  natural  causes,  101,  142;  generally  disap- 
pear after  being  in  excess,  115. 

Iron  contained  in  the  potatoe,  22. 

Jerusalem  artichoke  attacked  by  the  Aphis  vastator,  88. 

Kirby  and  Spence,  account  of  plagues  of  insects,  97-99. 

Lady-bird  destroys  the  Aphides,  103  ;  vast  numbers  of,  in  1807,  104. 

Larch  attacked  by  an  Aphis,  93. 

Latham's  account  of  the  potatoe  disease,  46. 

Light  necessary  for  the  growth  of  plants,  49 ;  influence  of  on  the 
potatoe,  ib. 

Locust,  effects  of,  99  ;  appearance  of,  this  year,  101. 

Mallow  attacked  by  the  Aphis  vastator,  88. 

Mangel  wurzel  attacked  by  the  Aphis  vastator.  79. 

Manures,  their  influence  on  the  potatoe  disease,  54,  55. 

Marigold  attacked  by  Aphis  vastator,  90. 

Marshall's  experiments  on  the  exhalation  of  water  by  the  potatoe 
plant,  5. 

Martius,  the  first  writer  on  the  potatoe  disease,  xxvii. 

Michael le's  analysis  of  the  potatoe,  18. 

Microscope  needful  for  the  investigation  of  the  disease,  xxxii.  ;  de- 
scription of  a  suitable  one,  xxxiii. 

Moisture,  effect  of,  on  the  potatoe  disease,  50  ;  on  potatoe  tubers,  51. 

Mortality  caused  by  decaying  insects,  99. 

Nectarine  attacked  by  the  Aphis  vastator,  90. 

Nettle  attacked  by  the  Aphis  vastator,  88. 

Nitrogen  exists  in  the  potatoe,  4 ;  its  probable  source,  ib. ;  its  rela- 
tive quantity  in  the  potatoe  and  in  other  articles  of  food,  20,  21. 

Oat  exempt  from  the  attack  of  the  Aphis  vastator,  87  ;  attacked  by 
another  Aphis,  ib. 

Old  age  of  the  varieties  of  potatoes  not  the  cause  of  the  disease,  46. 

Parasites  of  Aphides,  102. 

Parasitic  life,  curious  instance  of,  105. 

Parsnip  attacked  by  the  Aphis  vastator,  89  ;  by  another  Aphis,  ib. 

Pea  attacked  by  an  Aphis,  92  ;  occasional  effect  of  the  Aphis  on  the 
crop, ib. 

Peach  attacked  by  the  Aphis  vastator,  90. 


INDEX.  155 


Phosphorus  contained  in  the  potatoe,  22. 

Phosphorescence,  instances  of,  22. 

Plantain  attacked  by  the  Aphis  vastator,  89. 

Plusia  gamma,  increase  of,  in  1735,  98. 

Potatoe,  early  opinions  concerning,  9  ;  named  from  its  resemblance 
to  the  sweet  potatoe,  ib. ;  not  to  be  confounded  with  the  sweet 
potatoe,  15  ;  name  mentioned  by  Shakspeare,  ib. ;  qualities  of  the 
wild  potatoe,  11,  14;  analysis  of,  17,  18;  mode  of  analysis,  38; 
is  a  sufficient  source  of  nourishment  for  man,  20,  138,  143  ;  com- 
parative amount  of  nitrogen  in,  and  in  other  substances,  20,  21 ; 
quantity  necessary  to  sustain  life,  21  ;  fowls  will  not  feed  on  long, 
22;  contains  phosphorus,  ib.  ;  instances  of  phosphorescence,  ib.; 
contains  iron,  ib. ;  modes  of  cooking,  23 ;  domestic  uses  of,  23,  24  ; 
may  be  made  into  bread,  23  ;  in  wheaten  bread,  ib  ;  use  as  a  me- 
dicine, ib. ;  starch.  See  Starch.  Distillation  of  spirit  from,  25; 
wine  made  from,  26  ;  food  for  cattle,  ib. ;  mode  of  preserving  by 
the  Mexicans,  ib. ;  extent  of  distribution,  ib.  :  analysis  of,  in  vari- 
ous years,  39  ;  consequence  of  depending  solely  upon,  139  ;  illus- 
trated in  the  Irish,  ib. ;  mischievous  in  a  political  point  of  view, 
139,  144. 

Potatoe  disease,  27  ;  has  existed  in  Germany  since  1830,  xxvii.  ;  is 
mortification  or  gangrene,  27,  141  ;  commences  at  various  parts  of 
the  plant,  27  ;  various  modes  and  localities  of  attack,  28,  30 ;  fre- 
quently attacks  the  collar,  29 ;  various  modes  of  death  of  the 
plant,  ib. ;  causes  an  offensive  odor,  30 ;  probably  connected  with 
the  sap  and  cellular  tissue,  33  ;  probably  affects  every  part  of  a 
diseased  plant,  34  ;  attack  commences  at  all  ages  and  stages  of 
growth,  ib. ;  variety  of  effects  upon  the  tuber,  34,  35 ;  effects  upon 
the  structure  of  the  plant,  36;  analysis  of  diseased  tubers,  38,  39; 
does  not  cause  destruction  of  the  starch,  39,  40  ;  causes  develop- 
ment of  sugar,  and  gives  a  proneness  to  putrefaction,  40  ;  may 
be  produced  in  the  produce  of  diseased  tubers  without  the  reap- 
plication  of  the  exciting  cause,  34,  142  ;  course  of  when  it  ap- 
pears as  gangrena  sicca,  35 ;  result  of  cutting  the  haulm,  36,  123  ; 
attacks  new  and  old  varieties,  41  ;  resisted  by  the  wild  plant,  42, 
112;  attacks  varieties  variously,  43  ;  account  of  by  Mr.  Greatrex, 
ib. ;  by  Mr.  Storr,  44  ;  by  Mr.  Latham,  ib  ;  old  age  not  the  cause 
of,  ib.;  early  kinds  less  liable  to,  ib.;  not  caused  by  internal  agency, 
ib. ;  by  variations  of  temperature,  45  ;  by  variations  of  light,  ib. ; 
by  electricity,  ib. ;  by  excessive  moisture  or  draught,  46 ;  by  other 
atmospheric  causes,  ib. ;  effects  of  heat  and  moisture  on,  45  ;  not 
affected  by  soil,  ib  ;  by  manures,  54  ;  by  mode  of  culture,  ib. ;  re- 
lation of  fungi  to,  55,  56;  not  caused  by  fungi,  56;  relation  of 
insects  to,  57  ;  always  preceded  by  the  Aphis  vastator,  72,  111  ; 
mode  of  action  of  the  Aphis  vastator,  72,  1 12  ;  caused  by  the  Aphis 
vastator,  111,  141  ;  theory  of,  112 ;  will  probably  wear  out,  113 ; 
future  prospects  of,  115,  142;  remedies  for:  employing  early 
kinds,  122 ;  autumn  planting,  ib. ;  contagious  nature  of,  ib.  ;  crops 


156  INDEX. 


should  be  isolated,  123  ;  remedies  against  propagation  of,  ib. ; 
small  sets  recommended,  124  ;  production  of  fibre  essential,  ib. ; 
means  of  inducing  development  of  fibre,  ib  ;  remedies  against 
consequences  of,  125;  starch  available,  ib. ;  no  chemical  remedy 
of  use,  126 ;  drying,  ib.  ;  cold  dry  atmosphere  best  preservative, 
ib.  ;  probable  means  of  lessening,  142. 

Potatoe  plant,  general  description  of,  1,  6, 139  ;  root  and  leaf  essen- 
tial parts  of,  6  ;  individuality  of,  6,  15  ;  seedlings  are  individuals, 
7 ;  mode  of  obtaining  new  varieties,  ib. ;  duration  of  life  of  an 
individual,  8;  probably  limited,  ib. ;  belongs  to  a  poisonous  fa- 
mily, and  is  itself  poisonous,  ib. ;  first  figured  by  Gerard,  ib. ; 
description  of,  by  Gerard,  ib. ;  various  accounts  of  its  original 
source,  ib. ;  does  not  grow  wild  in  North  America,  9  ;  grows 
wild  in  Chili  and  Peru,  10 ;  wild  plants  at  Chelsea  and  Chiswick, 
12,13;  resist  the  disease,  43 ;  number  of  varieties,  13,14;  proba- 
ble source  of  our  varieties,  14;  mode  of  continuing  varieties,  15; 
the  varieties  in  use  are  deviations  from  the  natural  plant,  112, 

'  139;  tubers  of  wild  potatoe  brought  into  this  country  lately,  11, 
14  ;  minute  description  of  plants  and  produce  of  the  wild  tubers, 
12,  14;  analysis  of,  16  ;  fruit  used  as  a  pickle,  26  ;  effects  of  tem- 
perature on,  47  ;  of  light,  48  ;  of  electricity,  49;  of  drought  and 
moisture,  49,  50  ;  of  atmospheric  changes,  52  ;  soil  best  adapted 
for,  ib. ;  attacked  by  the  Aphis  vastator,  68 ;  mode  of  attack,  69, 
72 ;  attacked  by  other  diseases,  108 ;  curl,  ib. ;  description  of, 
103,  109  ;  probably  owing  to  Aphides,  110  ;  rust,  ib. ;  amount  of 
deficiency  of  crop  in  1845  and  in  1846,  132  ;  affords  more  ali- 
mentary matter  than  any  other  plant,  138 ;  facility  of  cultiva- 
tion, ib. 

Rare  insects  unusually  common  in  1846,  101. 

Rose-trees  attacked  by  an  Aphis,  94. 

Rust  on  potatoe  plant,  110. 

Rye  a  substitute  for  other  grain,  132. 

Salter,  Dr.,  first  noticed  the  potatoe  disease  in  England, xxvii. 

Scarcity  in  1845  and  1846,  132;  amount  of,  ib. 

Schlossberger  and  Kempt's  table  of  nitrogen  in  varieties  of  food,  21. 

Shepherd's  purse  attacked  by  the  Aphis  vastator,  89. 

Soil,  its  influence  on  the  disease,  52,  53. 

Solanine,  17,  18;  analysis  of,  18. 

Solanaeae  generally  preferred  by  the  Aphis  vastator,  85. 

Solanum  dulcamara  attacked  by  the  Aphis  vastator,  84 ;  nigrum  at- 
tacked by  the  Aphis  vastator,  ib. 

Southwell,  Sir  Robert,  his  account  of  the  introduction  of  the  po- 
tatoe, 9. 

Spiders  destroy  Aphides,  106. 

Spinach  attacked  by  the  Aphis  vastator,  81  ;  mode  of  attack,  82; 
effect  of  rain  on  the  disease  in,  83. 

Spurge  attacked  by  the  Aphis  vastator,  89. 

Starch,  its  source  and  uses  in  the  potatoe  plant,  4  ;  state  in  which 


INDEX.  157 

it  exists  in  the  plant,  19;  composition  of,  ib. ;  quantity  variable, 
ib. ;  potatoe,  manufacture  of,  24  ;  uses  of,  25  ;  St.  Etienne's  ma- 
chine, 24  ;  conversion  of,  into  dextrine,  25  ;  manufacture  of 
sugar  from,  substituted  for  arrow-root,  24 ;  in  diseased  potatoes  : 
sometimes  superabundant,  39 ;  generally  deficient,  ib. ;  may  be 
extracted  for  useful  purposes,  41,  137,  138. 

Stramonium  attacked  by  the  Aphis  vastator,  85. 

Storr's  account  of  the  potatoe  disease,  46. 

Sugar  made  from  potatoe  starch,  25 ;  found  in  diseased  potatoes, 
41 ;  cane  affected  by  an  Aphis,  92. 

Sweet  potatoe.     See  Convolvulus  battata. 

Sycamore  attacked  by  an  Aphis,  92. 

Syrphidae  destroy  Aphides,  104. 

Temperature,  effects  of,  on  the  potatoe  plant,  48  ;  on  the  decay  of 
tubers,  48,  49. 

Tobacco  not  attacked  by  the  Aphis  vastator,  85. 

Tomato  attacked  by  the  Aphis  vastator,  86. 

Tuber.     See  Potatoe. 

Turnip  attacked  by  the  Aphis  vastator,  74  ;  mode  and  progress  of 
the  attack,  74,  79 ;  mode  and  progress  of  attack  similar  to  that 
in  the  potatoe,  79 ;  fingers  and  toes,  explanation  of,  75 ;  speedily 
becomes  putrid,  76 ;  bad  odor  exhaled  by,  ib. ;  attacked  by  fungi, 
ib. ;  attacked  also  by  the  Aphis  brassicae,  77  ;  preferred  to  the 
potatoe  by  the  Aphis  vastator,  78 ;  Swede  attacked  by  the  Aphis 
vastator,  ib. ;  to  a  less  extent,  ib. ;  crops  destroyed  by  the  flea  in 
1786,  98. 

Ure,  Dr.,  analysis  of  the  potatoe  plant  from,  17. 

Wasps  at  Selborne  in  1783,  100. 

Wheat  plants  attacked  by  the  Aphis  vastator,  86,  87 ;  by  another 
Aphis,  87. 

White,  Rev.  G.,  instances  of  excessive  numbers  of  insects,  99. 

Wild  potatoes  introduced  in  modern  times,  11, 14 ;  peculiarities  of, 
ib. ;  not  in  use  now,  17  ;  plants  resist  the  disease,  42,  43  ;  resist 
the  Aphis  vastator,  85. 

Wine  made  from  potatoes,  26. 


14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

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